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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Calculating_power" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Calculating_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Calculating power</span> </div> </a> <ul id="toc-Calculating_power-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Definitions" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Definitions"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Definitions</span> </div> </a> <button aria-controls="toc-Definitions-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Definitions subsection</span> </button> <ul id="toc-Definitions-sublist" class="vector-toc-list"> <li id="toc-Imperial_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Imperial_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Imperial horsepower</span> </div> </a> <ul id="toc-Imperial_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Metric_horsepower_(PS,_KM,_cv,_hk,_pk,_k,_ks,_ch)" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Metric_horsepower_(PS,_KM,_cv,_hk,_pk,_k,_ks,_ch)"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Metric horsepower (PS, KM, cv, hk, pk, k, ks, ch)</span> </div> </a> <ul id="toc-Metric_horsepower_(PS,_KM,_cv,_hk,_pk,_k,_ks,_ch)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Tax_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Tax_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Tax horsepower</span> </div> </a> <ul id="toc-Tax_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Electrical_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electrical_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Electrical horsepower</span> </div> </a> <ul id="toc-Electrical_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hydraulic_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Hydraulic_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Hydraulic horsepower</span> </div> </a> <ul id="toc-Hydraulic_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Boiler_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Boiler_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Boiler horsepower</span> </div> </a> <ul id="toc-Boiler_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Drawbar_power" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Drawbar_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Drawbar power</span> </div> </a> <ul id="toc-Drawbar_power-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-RAC_horsepower_(taxable_horsepower)" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#RAC_horsepower_(taxable_horsepower)"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.8</span> <span>RAC horsepower (taxable horsepower)</span> </div> </a> <ul id="toc-RAC_horsepower_(taxable_horsepower)-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Measurement" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Measurement"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Measurement</span> </div> </a> <button aria-controls="toc-Measurement-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Measurement subsection</span> </button> <ul id="toc-Measurement-sublist" class="vector-toc-list"> <li id="toc-Nominal_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Nominal_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Nominal horsepower</span> </div> </a> <ul id="toc-Nominal_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Indicated_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Indicated_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Indicated horsepower</span> </div> </a> <ul id="toc-Indicated_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Brake_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Brake_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Brake horsepower</span> </div> </a> <ul id="toc-Brake_horsepower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Shaft_horsepower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Shaft_horsepower"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Shaft horsepower</span> </div> </a> <ul id="toc-Shaft_horsepower-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Engine_power_test_standards" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Engine_power_test_standards"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Engine power test standards</span> </div> </a> <button aria-controls="toc-Engine_power_test_standards-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Engine power test standards subsection</span> </button> <ul id="toc-Engine_power_test_standards-sublist" class="vector-toc-list"> <li id="toc-Society_of_Automotive_Engineers/SAE_International" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Society_of_Automotive_Engineers/SAE_International"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Society of Automotive Engineers/SAE International</span> </div> </a> <ul id="toc-Society_of_Automotive_Engineers/SAE_International-sublist" class="vector-toc-list"> <li id="toc-Early_"SAE_horsepower"" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Early_"SAE_horsepower""> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1.1</span> <span>Early "SAE horsepower"</span> </div> </a> <ul id="toc-Early_"SAE_horsepower"-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-SAE_gross_power" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#SAE_gross_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1.2</span> <span>SAE gross power</span> </div> </a> <ul id="toc-SAE_gross_power-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-SAE_net_power" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#SAE_net_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1.3</span> <span>SAE net power</span> </div> </a> <ul id="toc-SAE_net_power-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-SAE_certified_power" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#SAE_certified_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1.4</span> <span>SAE certified power</span> </div> </a> <ul id="toc-SAE_certified_power-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Deutsches_Institut_für_Normung_70020_(DIN_70020)" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Deutsches_Institut_für_Normung_70020_(DIN_70020)"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span><i>Deutsches Institut für Normung</i> 70020 (DIN 70020)</span> </div> </a> <ul id="toc-Deutsches_Institut_für_Normung_70020_(DIN_70020)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-CUNA" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#CUNA"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>CUNA</span> </div> </a> <ul id="toc-CUNA-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Economic_Commission_for_Europe_R24" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Economic_Commission_for_Europe_R24"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Economic Commission for Europe R24</span> </div> </a> <ul id="toc-Economic_Commission_for_Europe_R24-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Economic_Commission_for_Europe_R85" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Economic_Commission_for_Europe_R85"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.5</span> <span>Economic Commission for Europe R85</span> </div> </a> <ul id="toc-Economic_Commission_for_Europe_R85-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-80/1269/EEC" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#80/1269/EEC"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.6</span> <span>80/1269/EEC</span> </div> </a> <ul id="toc-80/1269/EEC-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-International_Organization_for_Standardization" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#International_Organization_for_Standardization"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.7</span> <span>International Organization for Standardization</span> </div> </a> <ul id="toc-International_Organization_for_Standardization-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Japanese_Industrial_Standard_D_1001" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Japanese_Industrial_Standard_D_1001"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.8</span> <span>Japanese Industrial Standard D 1001</span> </div> </a> <ul id="toc-Japanese_Industrial_Standard_D_1001-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Horsepower</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 73 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-73" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">73 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AD%D8%B5%D8%A7%D9%86_(%D9%88%D8%AD%D8%AF%D8%A9_%D9%82%D8%AF%D8%B1%D8%A9)" title="حصان (وحدة قدرة) – Arabic" lang="ar" hreflang="ar" data-title="حصان (وحدة قدرة)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/At_g%C3%BCc%C3%BC" title="At gücü – Azerbaijani" lang="az" hreflang="az" data-title="At gücü" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/B%C3%A9-la%CC%8Dt" title="Bé-la̍t – Minnan" lang="nan" hreflang="nan" data-title="Bé-la̍t" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BD%D1%81%D0%BA%D0%B0%D1%8F_%D1%81%D1%96%D0%BB%D0%B0" title="Конская сіла – Belarusian" lang="be" hreflang="be" data-title="Конская сіла" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BD%D1%81%D0%BA%D0%B0%D1%8F_%D1%81%D1%96%D0%BB%D0%B0" title="Конская сіла – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Конская сіла" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BD%D1%81%D0%BA%D0%B0_%D1%81%D0%B8%D0%BB%D0%B0" title="Конска сила – Bulgarian" lang="bg" hreflang="bg" data-title="Конска сила" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Cavall_de_vapor" title="Cavall de vapor – Catalan" lang="ca" hreflang="ca" data-title="Cavall de vapor" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Ko%C5%88sk%C3%A1_s%C3%ADla" title="Koňská síla – Czech" lang="cs" hreflang="cs" data-title="Koňská síla" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Hestekraft" title="Hestekraft – Danish" lang="da" hreflang="da" data-title="Hestekraft" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-ary mw-list-item"><a href="https://ary.wikipedia.org/wiki/%D8%B9%D9%88%D8%AF%D8%A7%D9%86_(%D8%B9%D8%A8%D8%B1%D8%A9_%D8%AF_%D9%84%D9%82%D8%AF%D8%B1%D8%A9)" title="عودان (عبرة د لقدرة) – Moroccan Arabic" lang="ary" hreflang="ary" data-title="عودان (عبرة د لقدرة)" data-language-autonym="الدارجة" data-language-local-name="Moroccan Arabic" class="interlanguage-link-target"><span>الدارجة</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Pferdest%C3%A4rke" title="Pferdestärke – German" lang="de" hreflang="de" data-title="Pferdestärke" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Hobuj%C3%B5ud" title="Hobujõud – Estonian" lang="et" hreflang="et" data-title="Hobujõud" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%8A%CF%80%CF%80%CE%BF%CF%82_(%CE%BC%CE%BF%CE%BD%CE%AC%CE%B4%CE%B1_%CE%B9%CF%83%CF%87%CF%8D%CE%BF%CF%82)" title="Ίππος (μονάδα ισχύος) – Greek" lang="el" hreflang="el" data-title="Ίππος (μονάδα ισχύος)" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Caballo_de_vapor" title="Caballo de vapor – Spanish" lang="es" hreflang="es" data-title="Caballo de vapor" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/%C4%88evalpovo" title="Ĉevalpovo – Esperanto" lang="eo" hreflang="eo" data-title="Ĉevalpovo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Zaldi-potentzia" title="Zaldi-potentzia – Basque" lang="eu" hreflang="eu" data-title="Zaldi-potentzia" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A7%D8%B3%D8%A8_%D8%A8%D8%AE%D8%A7%D8%B1" title="اسب بخار – Persian" lang="fa" hreflang="fa" data-title="اسب بخار" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Cheval-vapeur" title="Cheval-vapeur – French" lang="fr" hreflang="fr" data-title="Cheval-vapeur" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Hynstekr%C3%AAft" title="Hynstekrêft – Western Frisian" lang="fy" hreflang="fy" data-title="Hynstekrêft" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target"><span>Frysk</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Each-chumhacht" title="Each-chumhacht – Irish" lang="ga" hreflang="ga" data-title="Each-chumhacht" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Cabalo_de_vapor" title="Cabalo de vapor – Galician" lang="gl" hreflang="gl" data-title="Cabalo de vapor" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%A7%88%EB%A0%A5" title="마력 – Korean" lang="ko" hreflang="ko" data-title="마력" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%81%D5%AB%D5%A1%D5%B8%D6%82%D5%AA" title="Ձիաուժ – Armenian" lang="hy" hreflang="hy" data-title="Ձիաուժ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%85%E0%A4%B6%E0%A5%8D%E0%A4%B5_%E0%A4%B6%E0%A4%95%E0%A5%8D%E0%A4%A4%E0%A4%BF" title="अश्व शक्ति – Hindi" lang="hi" hreflang="hi" data-title="अश्व शक्ति" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Konjska_snaga" title="Konjska snaga – Croatian" lang="hr" hreflang="hr" data-title="Konjska snaga" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Daya_kuda" title="Daya kuda – Indonesian" lang="id" hreflang="id" data-title="Daya kuda" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Hestafl" title="Hestafl – Icelandic" lang="is" hreflang="is" data-title="Hestafl" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Cavallo_vapore" title="Cavallo vapore – Italian" lang="it" hreflang="it" data-title="Cavallo vapore" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9B%D7%95%D7%97_%D7%A1%D7%95%D7%A1" title="כוח סוס – Hebrew" lang="he" hreflang="he" data-title="כוח סוס" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%85%E0%B2%B6%E0%B3%8D%E0%B2%B5_%E0%B2%B8%E0%B2%BE%E0%B2%AE%E0%B2%B0%E0%B3%8D%E0%B2%A5%E0%B3%8D%E0%B2%AF" title="ಅಶ್ವ ಸಾಮರ್ಥ್ಯ – Kannada" lang="kn" hreflang="kn" data-title="ಅಶ್ವ ಸಾಮರ್ಥ್ಯ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="Kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%AA%E1%83%AE%E1%83%94%E1%83%9C%E1%83%98%E1%83%A1_%E1%83%AB%E1%83%90%E1%83%9A%E1%83%90" title="ცხენის ძალა – Georgian" lang="ka" hreflang="ka" data-title="ცხენის ძალა" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%90%D1%82_%D0%BA%D2%AF%D1%88%D1%96" title="Ат күші – Kazakh" lang="kk" hreflang="kk" data-title="Ат күші" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/%C5%9Eiyana_hesp%C3%AE" title="Şiyana hespî – Kurdish" lang="ku" hreflang="ku" data-title="Şiyana hespî" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Zirgsp%C4%93ks" title="Zirgspēks – Latvian" lang="lv" hreflang="lv" data-title="Zirgspēks" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Arklio_galia" title="Arklio galia – Lithuanian" lang="lt" hreflang="lt" data-title="Arklio galia" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/L%C3%B3er%C5%91" title="Lóerő – Hungarian" lang="hu" hreflang="hu" data-title="Lóerő" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%95%E0%B5%81%E0%B4%A4%E0%B4%BF%E0%B4%B0%E0%B4%B6%E0%B4%95%E0%B5%8D%E0%B4%A4%E0%B4%BF" title="കുതിരശക്തി – Malayalam" lang="ml" hreflang="ml" data-title="കുതിരശക്തി" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kuasa_kuda" title="Kuasa kuda – Malay" lang="ms" hreflang="ms" data-title="Kuasa kuda" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D0%B8%D0%BD%D1%8B_%D1%85%D2%AF%D1%87" title="Морины хүч – Mongolian" lang="mn" hreflang="mn" data-title="Морины хүч" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%99%E1%80%BC%E1%80%84%E1%80%BA%E1%80%B8%E1%80%80%E1%80%B1%E1%80%AC%E1%80%84%E1%80%BA%E1%80%9B%E1%80%B1%E1%80%A1%E1%80%AC%E1%80%B8" title="မြင်းကောင်ရေအား – Burmese" lang="my" hreflang="my" data-title="မြင်းကောင်ရေအား" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Paardenkracht_(eenheid)" title="Paardenkracht (eenheid) – Dutch" lang="nl" hreflang="nl" data-title="Paardenkracht (eenheid)" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ne mw-list-item"><a href="https://ne.wikipedia.org/wiki/%E0%A4%B9%E0%A4%B0%E0%A5%8D%E0%A4%B8_%E0%A4%AA%E0%A4%BE%E0%A4%B5%E0%A4%B0" title="हर्स पावर – Nepali" lang="ne" hreflang="ne" data-title="हर्स पावर" data-language-autonym="नेपाली" data-language-local-name="Nepali" class="interlanguage-link-target"><span>नेपाली</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E9%A6%AC%E5%8A%9B" title="馬力 – Japanese" lang="ja" hreflang="ja" data-title="馬力" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/PS" title="PS – Northern Frisian" lang="frr" hreflang="frr" data-title="PS" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Hestekraft" title="Hestekraft – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Hestekraft" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Hestekraft" title="Hestekraft – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Hestekraft" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Ot_kuchi" title="Ot kuchi – Uzbek" lang="uz" hreflang="uz" data-title="Ot kuchi" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Ko%C5%84_mechaniczny" title="Koń mechaniczny – Polish" lang="pl" hreflang="pl" data-title="Koń mechaniczny" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt badge-Q70893996 mw-list-item" title=""><a href="https://pt.wikipedia.org/wiki/Cavalo-vapor" title="Cavalo-vapor – Portuguese" lang="pt" hreflang="pt" data-title="Cavalo-vapor" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Cal_putere" title="Cal putere – Romanian" lang="ro" hreflang="ro" data-title="Cal putere" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-rue mw-list-item"><a href="https://rue.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BD%D1%8C%D1%81%D0%BA%D0%B0_%D1%81%D0%B8%D0%BB%D0%B0" title="Коньска сила – Rusyn" lang="rue" hreflang="rue" data-title="Коньска сила" data-language-autonym="Русиньскый" data-language-local-name="Rusyn" class="interlanguage-link-target"><span>Русиньскый</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9B%D0%BE%D1%88%D0%B0%D0%B4%D0%B8%D0%BD%D0%B0%D1%8F_%D1%81%D0%B8%D0%BB%D0%B0" title="Лошадиная сила – Russian" lang="ru" hreflang="ru" data-title="Лошадиная сила" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Horsepouer" title="Horsepouer – Scots" lang="sco" hreflang="sco" data-title="Horsepouer" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Kuajfuqi" title="Kuajfuqi – Albanian" lang="sq" hreflang="sq" data-title="Kuajfuqi" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Horsepower" title="Horsepower – Simple English" lang="en-simple" hreflang="en-simple" data-title="Horsepower" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/K%C3%B4%C5%88_(jednotka)" title="Kôň (jednotka) – Slovak" lang="sk" hreflang="sk" data-title="Kôň (jednotka)" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Konjska_mo%C4%8D" title="Konjska moč – Slovenian" lang="sl" hreflang="sl" data-title="Konjska moč" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9A%D0%BE%D1%9A%D1%81%D0%BA%D0%B0_%D1%81%D0%BD%D0%B0%D0%B3%D0%B0" title="Коњска снага – Serbian" lang="sr" hreflang="sr" data-title="Коњска снага" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Konjska_snaga" title="Konjska snaga – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Konjska snaga" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Hevosvoima" title="Hevosvoima – Finnish" lang="fi" hreflang="fi" data-title="Hevosvoima" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/H%C3%A4stkraft" title="Hästkraft – Swedish" lang="sv" hreflang="sv" data-title="Hästkraft" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%95%E0%AF%81%E0%AE%A4%E0%AE%BF%E0%AE%B0%E0%AF%88%E0%AE%A4%E0%AF%8D_%E0%AE%A4%E0%AE%BF%E0%AE%B1%E0%AE%A9%E0%AF%8D" title="குதிரைத் திறன் – Tamil" lang="ta" hreflang="ta" data-title="குதிரைத் திறன்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%85%E0%B0%B6%E0%B1%8D%E0%B0%B5_%E0%B0%B8%E0%B0%BE%E0%B0%AE%E0%B0%B0%E0%B1%8D%E0%B0%A5%E0%B1%8D%E0%B0%AF%E0%B0%82" title="అశ్వ సామర్థ్యం – Telugu" lang="te" hreflang="te" data-title="అశ్వ సామర్థ్యం" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%81%E0%B8%A3%E0%B8%87%E0%B8%A1%E0%B9%89%E0%B8%B2" title="แรงม้า – Thai" lang="th" hreflang="th" data-title="แรงม้า" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Beygir_g%C3%BCc%C3%BC" title="Beygir gücü – Turkish" lang="tr" hreflang="tr" data-title="Beygir gücü" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-tk mw-list-item"><a href="https://tk.wikipedia.org/wiki/At_g%C3%BC%C3%BD%C2%ADji" title="At güýji – Turkmen" lang="tk" hreflang="tk" data-title="At güýji" data-language-autonym="Türkmençe" data-language-local-name="Turkmen" class="interlanguage-link-target"><span>Türkmençe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9A%D1%96%D0%BD%D1%81%D1%8C%D0%BA%D0%B0_%D1%81%D0%B8%D0%BB%D0%B0" title="Кінська сила – Ukrainian" lang="uk" hreflang="uk" data-title="Кінська сила" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%A7%D8%B3%D9%BE%DB%8C_%D8%B7%D8%A7%D9%82%D8%AA" title="اسپی طاقت – Urdu" lang="ur" hreflang="ur" data-title="اسپی طاقت" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/M%C3%A3_l%E1%BB%B1c" title="Mã lực – 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<div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Unit of power with different values</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/Horsepower_(disambiguation)" class="mw-redirect mw-disambig" title="Horsepower (disambiguation)">Horsepower (disambiguation)</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox ib-unit"><tbody><tr><th colspan="2" class="infobox-above">Horsepower</th></tr><tr><td colspan="2" class="infobox-image notheme" style="background-color: #f8f9fa;"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:Imperial_Horsepower.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Imperial_Horsepower.svg/220px-Imperial_Horsepower.svg.png" decoding="async" width="220" height="127" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Imperial_Horsepower.svg/330px-Imperial_Horsepower.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Imperial_Horsepower.svg/440px-Imperial_Horsepower.svg.png 2x" data-file-width="716" data-file-height="414" /></a></span><div class="infobox-caption">One <i>imperial horsepower</i> lifts 550 <a href="/wiki/Pound_(mass)" title="Pound (mass)">pounds</a> (250 kg) by 1 <a href="/wiki/Foot_(unit)" title="Foot (unit)">foot</a> (30 cm) in 1 <a href="/wiki/Second" title="Second">second</a>.</div></td></tr><tr><th colspan="2" class="infobox-header">General information</th></tr><tr><th scope="row" class="infobox-label">Unit of</th><td class="infobox-data"><a href="/wiki/Power_(physics)" title="Power (physics)">power</a></td></tr><tr><th scope="row" class="infobox-label">Symbol</th><td class="infobox-data">hp</td></tr></tbody></table><style data-mw-deduplicate="TemplateStyles:r1236303919">@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-has-images-with-white-backgrounds img{background:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-has-images-with-white-backgrounds img{background:white}}</style> <p><b>Horsepower</b> (<b>hp</b>) is a <a href="/wiki/Unit_of_measurement" title="Unit of measurement">unit of measurement</a> of <a href="/wiki/Power_(physics)" title="Power (physics)">power</a>, or the rate at which <a href="/wiki/Work_(physics)" title="Work (physics)">work</a> is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the <b>imperial horsepower</b> as in "hp" or "bhp" which is about 745.7 <a href="/wiki/Watt" title="Watt">watts</a>, and the <b>metric horsepower</b> as in "cv" or "PS" which is approximately 735.5 watts. </p><p>The term was adopted in the late 18th century by <a href="/wiki/Scottish_people" title="Scottish people">Scottish</a> engineer <a href="/wiki/James_Watt" title="James Watt">James Watt</a> to compare the output of <a href="/wiki/Steam_engine" title="Steam engine">steam engines</a> with the power of <a href="/wiki/Draft_horse" title="Draft horse">draft horses</a>. It was later expanded to include the output power of other power-generating machinery such as <a href="/wiki/Piston_engines" class="mw-redirect" title="Piston engines">piston engines</a>, <a href="/wiki/Turbine" title="Turbine">turbines</a>, and <a href="/wiki/Electric_motor" title="Electric motor">electric motors</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The definition of the unit varied among geographical regions. Most countries now use the <a href="/wiki/International_System_of_Units" title="International System of Units">SI</a> unit <a href="/wiki/Watt" title="Watt">watt</a> for measurement of power. With the implementation of the EU Directive <a href="/wiki/Units_of_Measure_Directive#Directive_80/181/EEC" class="mw-redirect" title="Units of Measure Directive">80/181/EEC</a> on 1 January 2010,<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> the use of horsepower in the EU is permitted only as a supplementary unit. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c0/6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg/220px-6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg" decoding="async" width="220" height="157" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c0/6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg/330px-6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c0/6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg/440px-6_horse_team_East_Lampeter_TWP_LanCo_PA_1.jpg 2x" data-file-width="3857" data-file-height="2755" /></a><figcaption>A team of six horses mowing hay in <a href="/wiki/East_Lampeter_Township,_Pennsylvania" title="East Lampeter Township, Pennsylvania">East Lampeter Township, Pennsylvania</a>, U.S.</figcaption></figure> <p>The development of the <a href="/wiki/Steam_engine" title="Steam engine">steam engine</a> provided a reason to compare the output of horses with that of the engines that could replace them. In 1702, <a href="/wiki/Thomas_Savery" title="Thomas Savery">Thomas Savery</a> wrote in <i>The Miner's Friend</i>:<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <dl><dd>So that an engine which will raise as much water as two horses, working together at one time in such a work, can do, and for which there must be constantly kept ten or twelve horses for doing the same. Then I say, such an engine may be made large enough to do the work required in employing eight, ten, fifteen, or twenty horses to be constantly maintained and kept for doing such a work...</dd></dl> <p>The idea was later used by <a href="/wiki/James_Watt" title="James Watt">James Watt</a> to help market his improved steam engine. He had previously agreed to take royalties of one-third of the savings in coal from the older <a href="/wiki/Newcomen_steam_engine" class="mw-redirect" title="Newcomen steam engine">Newcomen steam engines</a>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> This royalty scheme did not work with customers who did not have existing steam engines but used horses instead. </p><p>Watt determined that a horse could turn a <a href="/wiki/Horse_mill" title="Horse mill">mill wheel</a> 144 times in an hour (or 2.4 times a minute).<sup id="cite_ref-Engineers121_6-0" class="reference"><a href="#cite_note-Engineers121-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The wheel was 12 feet (3.7 m) in radius; therefore, the horse travelled <span class="nowrap">2.4 × 2π × 12</span> feet in one minute. Watt judged that the horse could pull with a <a href="/wiki/Force" title="Force">force</a> of 180 pounds-force (800 N).<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> So: </p> <dl><dd><span class="mwe-math-element" data-qid="Q120634922"><a href="/w/index.php?title=Special:MathWikibase&qid=Q120634922" style="color:inherit;"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P={\frac {W}{t}}={\frac {Fd}{t}}={\frac {180~{\text{lbf}}\times 2.4\times 2\,\pi \times 12~{\text{ft}}}{1~{\text{min}}}}=32{,}572~{\frac {{\text{ft}}\cdot {\text{lbf}}}{\text{min}}}.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>P</mi> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>W</mi> <mi>t</mi> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi>F</mi> <mi>d</mi> </mrow> <mi>t</mi> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>180</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>lbf</mtext> </mrow> <mo>×</mo> <mn>2.4</mn> <mo>×</mo> <mn>2</mn> <mspace width="thinmathspace" /> <mi>π</mi> <mo>×</mo> <mn>12</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>ft</mtext> </mrow> </mrow> <mrow> <mn>1</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>min</mtext> </mrow> </mrow> </mfrac> </mrow> <mo>=</mo> <mn>32,572</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>ft</mtext> </mrow> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mtext>lbf</mtext> </mrow> </mrow> <mtext>min</mtext> </mfrac> </mrow> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P={\frac {W}{t}}={\frac {Fd}{t}}={\frac {180~{\text{lbf}}\times 2.4\times 2\,\pi \times 12~{\text{ft}}}{1~{\text{min}}}}=32{,}572~{\frac {{\text{ft}}\cdot {\text{lbf}}}{\text{min}}}.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8c92b860ac146795dd65f96ed1d1d51a787b3543" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:62.125ex; height:5.343ex;" alt="{\displaystyle P={\frac {W}{t}}={\frac {Fd}{t}}={\frac {180~{\text{lbf}}\times 2.4\times 2\,\pi \times 12~{\text{ft}}}{1~{\text{min}}}}=32{,}572~{\frac {{\text{ft}}\cdot {\text{lbf}}}{\text{min}}}.}"></a></span></dd></dl> <p><i>Engineering in History</i> recounts that <a href="/wiki/John_Smeaton" title="John Smeaton">John Smeaton</a> initially estimated that a horse could produce 22,916 foot-pounds (31,070 J) per minute.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> <a href="/wiki/John_Theophilus_Desaguliers" title="John Theophilus Desaguliers">John Desaguliers</a> had previously suggested 44,000 foot-pounds (59,656 J) per minute, and <a href="/wiki/Thomas_Tredgold" title="Thomas Tredgold">Thomas Tredgold</a> suggested 27,500 foot-pounds (37,285 J) per minute. "Watt found by experiment in 1782 that a '<a href="/wiki/Draft_horse" title="Draft horse">brewery horse</a>' could produce 32,400 foot-pounds [43,929 J] per minute."<sup id="cite_ref-kirby-p171_9-0" class="reference"><a href="#cite_note-kirby-p171-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> James Watt and <a href="/wiki/Matthew_Boulton" title="Matthew Boulton">Matthew Boulton</a> standardized that figure at 33,000 foot-pounds (44,742 J) per minute the next year.<sup id="cite_ref-kirby-p171_9-1" class="reference"><a href="#cite_note-kirby-p171-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>A common legend states that the unit was created when one of Watt's first customers, a brewer, specifically demanded an engine that would match a horse, and chose the strongest horse he had and driving it to the limit. In that legend, Watt accepted the challenge and built a machine that was actually even stronger than the figure achieved by the brewer, and the output of that machine became the horsepower.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>In 1993, R. D. Stevenson and R. J. Wassersug published correspondence in <i><a href="/wiki/Nature_(journal)" title="Nature (journal)">Nature</a></i> summarizing measurements and calculations of peak and sustained work rates of a horse.<sup id="cite_ref-nature_11-0" class="reference"><a href="#cite_note-nature-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Citing measurements made at the 1926 <a href="/wiki/Iowa_State_Fair" title="Iowa State Fair">Iowa State Fair</a>, they reported that the peak power over a few seconds has been measured to be as high as 14.88 hp (11.10 kW)<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> and also observed that for sustained activity, a work rate of about 1 hp (0.75 kW) per horse is consistent with agricultural advice from both the 19th and 20th centuries and also consistent with a work rate of about four times the <a href="/wiki/Basal_rate" title="Basal rate">basal rate</a> expended by other vertebrates for sustained activity.<sup id="cite_ref-nature_11-1" class="reference"><a href="#cite_note-nature-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>When considering <a href="/wiki/Human_power" title="Human power">human-powered equipment</a>, a healthy human can produce about 1.2 hp (0.89 kW) briefly (see <a href="/wiki/Orders_of_magnitude_(power)" title="Orders of magnitude (power)">orders of magnitude</a>) and sustain about 0.1 hp (0.075 kW) indefinitely; trained athletes can manage up to about 2.5 hp (1.9 kW) briefly<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> and 0.35 hp (0.26 kW) for a period of several hours.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> The Jamaican sprinter <a href="/wiki/Usain_Bolt" title="Usain Bolt">Usain Bolt</a> produced a maximum of 3.5 hp (2.6 kW) 0.89 seconds into his 9.58 second 100-metre (109.4 yd) sprint world record in 2009.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability"><span title="The material near this tag failed verification of its source citation(s). (December 2023)">failed verification</span></a></i>]</sup> </p><p>In 2023 a group of engineers modified a <a href="/wiki/Dynometer" class="mw-redirect" title="Dynometer">dynometer</a> to be able to measure how much horsepower a horse can produce. This horse was measured to 5.7 hp (4.3 kW).<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Calculating_power">Calculating power</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=2" title="Edit section: Calculating power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>When <a href="/wiki/Torque" title="Torque">torque</a> <span class="texhtml mvar" style="font-style:italic;">T</span> is in <a href="/wiki/Pound-foot_(torque)" title="Pound-foot (torque)">pound-foot</a> units, <a href="/wiki/Rotational_speed" class="mw-redirect" title="Rotational speed">rotational speed</a> <span class="texhtml mvar" style="font-style:italic;">N</span> is in <a href="/wiki/Revolutions_per_minute" title="Revolutions per minute">rpm</a>, the resulting power in horsepower is </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {ft{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{5252}}.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo fence="false" stretchy="false">{</mo> <mi>P</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">p</mi> </mrow> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo fence="false" stretchy="false">{</mo> <mi>T</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">f</mi> <mi mathvariant="normal">t</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>⋅</mo> </mrow> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">f</mi> </mrow> </mrow> </msub> <mo fence="false" stretchy="false">{</mo> <mi>N</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">p</mi> <mi mathvariant="normal">m</mi> </mrow> </mrow> </msub> </mrow> <mn>5252</mn> </mfrac> </mrow> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {ft{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{5252}}.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/36439cd4d26ee91f97c36b30b5e695782594a5ef" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:26.146ex; height:5.676ex;" alt="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {ft{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{5252}}.}"></span><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></dd></dl> <p>The constant 5252 is the <a href="/wiki/Rounding" title="Rounding">rounded</a> value of (33,000 ft⋅lbf/min)/(2π rad/rev). </p><p>When torque <span class="texhtml mvar" style="font-style:italic;">T</span> is in inch-pounds, </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {in{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{63{,}025}}.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo fence="false" stretchy="false">{</mo> <mi>P</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">p</mi> </mrow> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo fence="false" stretchy="false">{</mo> <mi>T</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">i</mi> <mi mathvariant="normal">n</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>⋅</mo> </mrow> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">f</mi> </mrow> </mrow> </msub> <mo fence="false" stretchy="false">{</mo> <mi>N</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">p</mi> <mi mathvariant="normal">m</mi> </mrow> </mrow> </msub> </mrow> <mn>63,025</mn> </mfrac> </mrow> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {in{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{63{,}025}}.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ea2aa05ad712092adb73640373180065b05e59d6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:26.265ex; height:6.176ex;" alt="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{T\}_{\mathrm {in{\cdot }lbf} }\{N\}_{\mathrm {rpm} }}{63{,}025}}.}"></span></dd></dl> <p>The constant 63,025 is the approximation of </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 33{,}000~{\frac {{\text{ft}}{\cdot }{\text{lbf}}}{\text{min}}}\times {\frac {12~{\frac {\text{in}}{\text{ft}}}}{2\pi ~{\text{rad}}}}\approx 63{,}025{\frac {{\text{in}}{\cdot }{\text{lbf}}}{\text{min}}}.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>33,000</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>ft</mtext> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>⋅</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>lbf</mtext> </mrow> </mrow> <mtext>min</mtext> </mfrac> </mrow> <mo>×</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>12</mn> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mtext>in</mtext> <mtext>ft</mtext> </mfrac> </mrow> </mrow> <mrow> <mn>2</mn> <mi>π</mi> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>rad</mtext> </mrow> </mrow> </mfrac> </mrow> <mo>≈</mo> <mn>63,025</mn> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>in</mtext> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>⋅</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>lbf</mtext> </mrow> </mrow> <mtext>min</mtext> </mfrac> </mrow> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 33{,}000~{\frac {{\text{ft}}{\cdot }{\text{lbf}}}{\text{min}}}\times {\frac {12~{\frac {\text{in}}{\text{ft}}}}{2\pi ~{\text{rad}}}}\approx 63{,}025{\frac {{\text{in}}{\cdot }{\text{lbf}}}{\text{min}}}.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/aaec15793f5f8e1b99fdc4142bfef187692ffd40" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:39.187ex; height:6.676ex;" alt="{\displaystyle 33{,}000~{\frac {{\text{ft}}{\cdot }{\text{lbf}}}{\text{min}}}\times {\frac {12~{\frac {\text{in}}{\text{ft}}}}{2\pi ~{\text{rad}}}}\approx 63{,}025{\frac {{\text{in}}{\cdot }{\text{lbf}}}{\text{min}}}.}"></span></dd></dl> <div class="mw-heading mw-heading2"><h2 id="Definitions">Definitions</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=3" title="Edit section: Definitions"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Imperial_horsepower">Imperial horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=4" title="Edit section: Imperial horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Assuming the third <a href="/wiki/General_Conference_on_Weights_and_Measures" title="General Conference on Weights and Measures">CGPM</a> (1901, CR 70) definition of <a href="/wiki/Standard_gravity" title="Standard gravity">standard gravity</a>, <span class="nowrap"><i>g</i><sub>n</sub> = 9.80665 m/s<sup>2</sup></span>, is used to define the pound-force as well as the kilogram force, and the <a href="/wiki/International_avoirdupois_pound" class="mw-redirect" title="International avoirdupois pound">international avoirdupois pound</a> (1959), one imperial horsepower is: </p> <dl><dd><table> <tbody><tr> <td>1 hp </td> <td>≡ 33,000 ft·lbf/min </td> <td colspan="2">by definition </td></tr> <tr> <td> </td> <td>= 550 ft⋅lbf/s </td> <td>since </td> <td>1 min = 60 s </td></tr> <tr> <td> </td> <td>= 550 × 0.3048 × 0.45359237 m⋅<a href="/wiki/Kilogram-force" title="Kilogram-force">kgf</a>/s </td> <td>since </td> <td>1 ft ≡ 0.3048 m and 1 lb ≡ 0.45359237 kg </td></tr> <tr> <td> </td> <td>= 76.0402249068 kg<sub>f</sub>⋅m/s </td> <td> </td> <td> </td></tr> <tr> <td> </td> <td>= 76.0402249068 × 9.80665 kg⋅m<sup>2</sup>/s<sup>3</sup> </td> <td>since </td> <td><i>g</i> = 9.80665 m/s<sup>2</sup> </td></tr> <tr> <td> </td> <td>= 745.69987158227022 W ≈ 745.700 W </td> <td>since </td> <td>1 W ≡ 1 <a href="/wiki/Joule" title="Joule">J</a>/s = 1 <a href="/wiki/Newton_(unit)" title="Newton (unit)">N</a>⋅m/s = 1 (kg⋅m/s<sup>2</sup>)⋅(m/s) </td></tr></tbody></table></dd></dl> <p>Or given that 1 hp = 550 ft⋅lbf/s, 1 ft = 0.3048 m, 1 lbf ≈ 4.448 N, 1 J = 1 N⋅m, 1 W = 1 J/s: 1 hp ≈ 745.7 W </p> <div class="mw-heading mw-heading3"><h3 id="Metric_horsepower_(PS,_KM,_cv,_hk,_pk,_k,_ks,_ch)"><span id="Metric_horsepower_.28PS.2C_KM.2C_cv.2C_hk.2C_pk.2C_k.2C_ks.2C_ch.29"></span><span class="anchor" id="Metric_horsepower"></span><span class="anchor" id="Metric"></span><span class="anchor" id="PS"></span><span class="anchor" id="cv"></span><span class="anchor" id="hk"></span><span class="anchor" id="pk"></span><span class="anchor" id="ks"></span><span class="anchor" id="ch"></span> Metric horsepower (PS, KM, cv, hk, pk, k, ks, ch)</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=5" title="Edit section: Metric horsepower (PS, KM, cv, hk, pk, k, ks, ch)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Horsepower_plain.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Horsepower_plain.svg/220px-Horsepower_plain.svg.png" decoding="async" width="220" height="127" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Horsepower_plain.svg/330px-Horsepower_plain.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Horsepower_plain.svg/440px-Horsepower_plain.svg.png 2x" data-file-width="716" data-file-height="414" /></a><figcaption>One <i>metric horsepower</i> is needed to lift 75 <a href="/wiki/Kilogram" title="Kilogram">kilograms</a> by 1 <a href="/wiki/Metre" title="Metre">metre</a> in 1 <a href="/wiki/Second" title="Second">second</a>.</figcaption></figure> <p>The various units used to indicate this definition (<i>PS</i>, <i> KM</i>, <i>cv</i>, <i>hk</i>, <i>pk</i>, <i>k</i>, <i>ks</i> and <i>ch</i>) all translate to <i>horse power</i> in English. British manufacturers often intermix metric horsepower and mechanical horsepower depending on the origin of the engine in question.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2024)">citation needed</span></a></i>]</sup> </p><p><a href="/wiki/Deutsches_Institut_f%C3%BCr_Normung" title="Deutsches Institut für Normung">DIN</a> 66036 defines one metric horsepower as the power to raise a mass of 75 kilograms against the Earth's gravitational force over a distance of one metre in one second:<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> <span class="nowrap">75 kg × 9.80665 m/s<sup>2</sup> × 1 m / 1 s</span> = 75 <a href="/wiki/Kilogram-force" title="Kilogram-force"><abbr title="Kilogram-force">kgf</abbr></a>⋅m/s = 1 PS. This is equivalent to 735.49875 W, or 98.6% of an imperial horsepower. In 1972, the PS was replaced by the <a href="/wiki/Kilowatt" class="mw-redirect" title="Kilowatt">kilowatt</a> as the official power-measuring unit in EEC directives.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </p><p>Other names for the metric horsepower are the Italian <span title="Italian-language text"><i lang="it">cavallo vapore (cv)</i></span>, Dutch <span title="Dutch-language text"><i lang="nl">paardenkracht (pk)</i></span>, the French <span title="French-language text"><i lang="fr">cheval-vapeur (ch)</i></span>, the Spanish <span title="Spanish-language text"><i lang="es">caballo de vapor</i></span> and Portuguese <span title="Portuguese-language text"><i lang="pt">cavalo-vapor (cv)</i></span>, the Russian <span title="Russian-language text"><span lang="ru">лошадиная сила (л. с.)</span></span>, the Swedish <span title="Swedish-language text"><i lang="sv">hästkraft (hk)</i></span>, the Finnish <span title="Finnish-language text"><i lang="fi">hevosvoima (hv)</i></span>, the Estonian <span title="Estonian-language text"><i lang="et">hobujõud (hj)</i></span>, the Norwegian and Danish <span title="Danish-language text"><i lang="da">hestekraft (hk)</i></span>, the Hungarian <span title="Hungarian-language text"><i lang="hu">lóerő (LE)</i></span>, the Czech <span title="Czech-language text"><i lang="cs">koňská síla</i></span> and Slovak <span title="Slovak-language text"><i lang="sk">konská sila (k</i></span> or <span title="Slovak-language text"><i lang="sk">ks</i></span>), the Serbo-Croatian <span title="Serbo-Croatian-language text"><i lang="sh">konjska snaga (KS)</i></span>, the Bulgarian <span title="Bulgarian-language text"><span lang="bg">конска сила</span></span>, the Macedonian <span title="Macedonian-language text"><span lang="mk">коњска сила (KC)</span></span>, the Polish <span title="Polish-language text"><i lang="pl">koń mechaniczny (KM)</i></span> (<abbr style="font-size:85%" title="literal translation">lit.</abbr><span style="white-space: nowrap;"> </span><span class="gloss-quot">'</span><span class="gloss-text">mechanical horse</span><span class="gloss-quot">'</span>), Slovenian <span title="Slovene-language text"><i lang="sl">konjska moč (KM)</i></span>, the Ukrainian <span title="Ukrainian-language text"><span lang="uk">кінська сила (к. с.)</span></span>, the Romanian <span title="Romanian-language text"><i lang="ro">cal-putere (CP)</i></span>, and the German <span title="German-language text"><i lang="de">Pferdestärke (PS)</i></span>. </p><p>In the 19th century, <a href="/wiki/French_Revolution" title="French Revolution">revolutionary-era France</a> had its own unit used to replace the <i>cheval vapeur</i> (horsepower); based on a 100 <a href="/wiki/Kilogram-force" title="Kilogram-force">kgf</a>⋅m/s standard, it was called the <a href="/wiki/Poncelet" title="Poncelet">poncelet</a> and was abbreviated <i>p</i>. </p> <div class="mw-heading mw-heading3"><h3 id="Tax_horsepower">Tax horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=6" title="Edit section: Tax horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Tax_horsepower" title="Tax horsepower">Tax horsepower</a></div> <p>Tax or fiscal horsepower is a non-linear rating of a motor vehicle for tax purposes.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> Tax horsepower ratings were originally more or less directly related to the size of the engine; but as of 2000, many countries changed over to systems based on CO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub> emissions, so are not directly comparable to older ratings.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> The <a href="/wiki/Citro%C3%ABn_2CV" title="Citroën 2CV">Citroën 2CV</a> is named for its French fiscal horsepower rating, "deux chevaux" (2CV).<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electrical_horsepower">Electrical horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=7" title="Edit section: Electrical horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Nameplates on electrical motors show their power output, not the power input (the power delivered at the shaft, not the power consumed to drive the motor). This power output is ordinarily stated in watts or kilowatts. In the United States, the power output is stated in horsepower which, for this purpose, is defined as exactly 746 W.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Hydraulic_horsepower">Hydraulic horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=8" title="Edit section: Hydraulic horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Hydraulic horsepower can represent the power available within <a href="/wiki/Hydraulic_machinery" title="Hydraulic machinery">hydraulic machinery</a>, power through the down-hole nozzle of a <a href="/wiki/Drilling_rig" title="Drilling rig">drilling rig</a>,<sup id="cite_ref-Schlumberger,_Hydraulic_horsepower_22-0" class="reference"><a href="#cite_note-Schlumberger,_Hydraulic_horsepower-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> or can be used to estimate the mechanical power needed to generate a known hydraulic flow rate. </p><p>It may be calculated as<sup id="cite_ref-Schlumberger,_Hydraulic_horsepower_22-1" class="reference"><a href="#cite_note-Schlumberger,_Hydraulic_horsepower-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{hydraulic power}}={\frac {{\text{pressure}}\times {\text{volumetric flow rate}}}{1714}},}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>hydraulic power</mtext> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mtext>pressure</mtext> </mrow> <mo>×</mo> <mrow class="MJX-TeXAtom-ORD"> <mtext>volumetric flow rate</mtext> </mrow> </mrow> <mn>1714</mn> </mfrac> </mrow> <mo>,</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{hydraulic power}}={\frac {{\text{pressure}}\times {\text{volumetric flow rate}}}{1714}},}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/438104f4c8f226b02ce5cba8049f9582f648b924" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:52.055ex; height:5.509ex;" alt="{\displaystyle {\text{hydraulic power}}={\frac {{\text{pressure}}\times {\text{volumetric flow rate}}}{1714}},}"></span></dd></dl> <p>where pressure is in psi, and flow rate is in <a href="/wiki/US_gallon" class="mw-redirect" title="US gallon">US gallons</a> per minute. </p><p>Drilling rigs are powered mechanically by rotating the drill pipe from above. Hydraulic power is still needed though, as 1 500 to 5 000 W are required to push <a href="/wiki/Drilling_mud" class="mw-redirect" title="Drilling mud">mud</a> through the drill bit to clear waste rock. Additional hydraulic power may also be used to drive a down-hole mud motor to power <a href="/wiki/Directional_drilling" title="Directional drilling">directional drilling</a>.<sup id="cite_ref-Schlumberger,_Hydraulic_horsepower_22-2" class="reference"><a href="#cite_note-Schlumberger,_Hydraulic_horsepower-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p><p>When using SI units, the equation becomes coherent and there is no dividing constant. </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{hydraulic power}}={\text{pressure}}\times {\text{volumetric flow rate}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>hydraulic power</mtext> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mtext>pressure</mtext> </mrow> <mo>×</mo> <mrow class="MJX-TeXAtom-ORD"> <mtext>volumetric flow rate</mtext> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{hydraulic power}}={\text{pressure}}\times {\text{volumetric flow rate}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e08f16f55ce3a96b05f201c77fda746f1cb5a46d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:50.572ex; height:2.509ex;" alt="{\displaystyle {\text{hydraulic power}}={\text{pressure}}\times {\text{volumetric flow rate}}}"></span></dd></dl> <p>where pressure is in pascals (Pa), and flow rate is in <a href="/wiki/Cubic_metre" title="Cubic metre">cubic metres</a> per second (m<sup>3</sup>). </p> <div class="mw-heading mw-heading3"><h3 id="Boiler_horsepower">Boiler horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=9" title="Edit section: Boiler horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Boiler horsepower is a <a href="/wiki/Steam_boiler" class="mw-redirect" title="Steam boiler">boiler</a>'s capacity to deliver <a href="/wiki/Steam" title="Steam">steam</a> to a <a href="/wiki/Steam_engine" title="Steam engine">steam engine</a> and is not the same unit of power as the 550 ft lb/s definition. One boiler horsepower is equal to the thermal energy rate required to evaporate 34.5 pounds (15.6 kg) of fresh water at 212 °F (100 °C) in one hour. In the early days of steam use, the boiler horsepower was roughly comparable to the horsepower of engines fed by the boiler.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p><p>The term "boiler horsepower" was originally developed at the <a href="/wiki/Philadelphia_Centennial_Exhibition" class="mw-redirect" title="Philadelphia Centennial Exhibition">Philadelphia Centennial Exhibition</a> in 1876, where the best steam engines of that period were tested. The average steam consumption of those engines (per output horsepower) was determined to be the evaporation of 30 pounds (14 kg) of water per hour, based on feed water at 100 °F (38 °C), and saturated steam generated at 70 psi (480 kPa). This original definition is equivalent to a boiler heat output of 33,485 Btu/h (9.813 kW). A few years later in 1884, the <a href="/wiki/American_Society_of_Mechanical_Engineers" title="American Society of Mechanical Engineers">ASME</a> re-defined the boiler horsepower as the thermal output equal to the evaporation of 34.5 pounds per hour of water "from and at" 212 °F (100 °C). This considerably simplified boiler testing, and provided more accurate comparisons of the boilers at that time. This revised definition is equivalent to a boiler heat output of 33,469 Btu/h (9.809 kW). Present industrial practice is to define "boiler horsepower" as a boiler thermal output equal to 33,475 Btu/h (9.811 kW), which is very close to the original and revised definitions. </p><p>Boiler horsepower is still used to measure boiler output in industrial boiler engineering in the US. Boiler horsepower is abbreviated BHP, which is also used in many places to symbolize brake horsepower. </p> <div class="mw-heading mw-heading3"><h3 id="Drawbar_power">Drawbar power</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=10" title="Edit section: Drawbar power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Power_at_rail" class="mw-redirect" title="Power at rail">Power at rail</a></div> <p>Drawbar power (dbp) is the power a <a href="/wiki/Railway" class="mw-redirect" title="Railway">railway</a> <a href="/wiki/Locomotive" title="Locomotive">locomotive</a> has available to haul a <a href="/wiki/Train" title="Train">train</a> or an agricultural tractor to pull an implement. This is a measured figure rather than a calculated one. A special <a href="/wiki/Railway_car" class="mw-redirect" title="Railway car">railway car</a> called a <a href="/wiki/Dynamometer_car" title="Dynamometer car">dynamometer car</a> coupled behind the locomotive keeps a continuous record of the <a href="/wiki/Drawbar_(haulage)" title="Drawbar (haulage)">drawbar</a> pull exerted, and the speed. From these, the power generated can be calculated. To determine the maximum power available, a controllable load is required; it is normally a second locomotive with its brakes applied, in addition to a static load. </p><p>If the drawbar force (<span class="texhtml mvar" style="font-style:italic;">F</span>) is measured in pounds-force (lbf) and speed (<span class="texhtml mvar" style="font-style:italic;">v</span>) is measured in miles per hour (mph), then the drawbar power (<span class="texhtml mvar" style="font-style:italic;">P</span>) in horsepower (hp) is </p><p><span class="mwe-math-element"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{F\}_{\mathrm {lbf} }\{v\}_{\mathrm {mph} }}{375}}.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo fence="false" stretchy="false">{</mo> <mi>P</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">p</mi> </mrow> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo fence="false" stretchy="false">{</mo> <mi>F</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">f</mi> </mrow> </mrow> </msub> <mo fence="false" stretchy="false">{</mo> <mi>v</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">p</mi> <mi mathvariant="normal">h</mi> </mrow> </mrow> </msub> </mrow> <mn>375</mn> </mfrac> </mrow> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{F\}_{\mathrm {lbf} }\{v\}_{\mathrm {mph} }}{375}}.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a0b7ae1ed6dbf75ad42018c7d1b193506951e123" class="mwe-math-fallback-image-display mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:23.875ex; height:5.843ex;" alt="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{F\}_{\mathrm {lbf} }\{v\}_{\mathrm {mph} }}{375}}.}"></span> </p><p>Example: How much power is needed to pull a drawbar load of 2,025 pounds-force at 5 miles per hour? </p><p><span class="mwe-math-element"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {2025\times 5}{375}}=27.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo fence="false" stretchy="false">{</mo> <mi>P</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">p</mi> </mrow> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>2025</mn> <mo>×</mo> <mn>5</mn> </mrow> <mn>375</mn> </mfrac> </mrow> <mo>=</mo> <mn>27.</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \{P\}_{\mathrm {hp} }={\frac {2025\times 5}{375}}=27.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0caaf23eb0bc954e66387b18027e1df5436babf2" class="mwe-math-fallback-image-display mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:24.788ex; height:5.343ex;" alt="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {2025\times 5}{375}}=27.}"></span> </p><p>The constant 375 is because 1 hp = 375 lbf⋅mph. If other units are used, the constant is different. When using coherent <a href="/wiki/SI" class="mw-redirect" title="SI">SI</a> units (watts, newtons, and metres per second), no constant is needed, and the formula becomes <span class="texhtml"><i>P</i> = <i>Fv</i></span>. </p><p>This formula may also be used to calculate the power of a jet engine, using the speed of the jet and the thrust required to maintain that speed. </p><p>Example: how much power is generated with a thrust of 4000 pounds at 400 miles per hour? </p><p><span class="mwe-math-element"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {4000\times 400}{375}}=4266.7.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo fence="false" stretchy="false">{</mo> <mi>P</mi> <msub> <mo fence="false" stretchy="false">}</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">p</mi> </mrow> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>4000</mn> <mo>×</mo> <mn>400</mn> </mrow> <mn>375</mn> </mfrac> </mrow> <mo>=</mo> <mn>4266.7.</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \{P\}_{\mathrm {hp} }={\frac {4000\times 400}{375}}=4266.7.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/745c926e4066178e599d725832efa531a47ae701" class="mwe-math-fallback-image-display mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:31.247ex; height:5.343ex;" alt="{\displaystyle \{P\}_{\mathrm {hp} }={\frac {4000\times 400}{375}}=4266.7.}"></span> </p> <div class="mw-heading mw-heading3"><h3 id="RAC_horsepower_(taxable_horsepower)"><span id="RAC_horsepower_.28taxable_horsepower.29"></span>RAC horsepower (taxable horsepower)</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=11" title="Edit section: RAC horsepower (taxable horsepower)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Tax_horsepower" title="Tax horsepower">Tax horsepower</a></div> <p>This measure was instituted by the <a href="/wiki/Royal_Automobile_Club" title="Royal Automobile Club">Royal Automobile Club</a> and was used to denote the power of early 20th-century British cars. Many cars took their names from this figure (hence the Austin Seven and Riley Nine), while others had names such as "40/50 hp", which indicated the RAC figure followed by the true measured power. </p><p>Taxable horsepower does not reflect developed horsepower; rather, it is a calculated figure based on the engine's bore size, number of cylinders, and a (now archaic) presumption of engine efficiency. As new engines were designed with ever-increasing efficiency, it was no longer a useful measure, but was kept in use by UK regulations, which used the rating for <a href="/wiki/Tax_horsepower" title="Tax horsepower">tax purposes</a>. The United Kingdom was not the only country that used the RAC rating; many states in Australia used RAC hp to determine taxation.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> The RAC formula was sometimes applied in British colonies as well, such as <a href="/wiki/Kenya_Colony" title="Kenya Colony">Kenya (British East Africa)</a>.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{RAC h.p.}}={\frac {D\times D\times n}{2.5}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>RAC h.p.</mtext> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi>D</mi> <mo>×</mo> <mi>D</mi> <mo>×</mo> <mi>n</mi> </mrow> <mn>2.5</mn> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{RAC h.p.}}={\frac {D\times D\times n}{2.5}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b76689b2fe0b580846151e6fdec268b23e180594" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:24.45ex; height:5.176ex;" alt="{\displaystyle {\text{RAC h.p.}}={\frac {D\times D\times n}{2.5}}}"></span></dd></dl> <p>where </p> <dl><dd><i>D</i> is the diameter (or <a href="/wiki/Bore_(engine)" title="Bore (engine)">bore</a>) of the cylinder in inches,</dd> <dd><i>n</i> is the number of cylinders.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup></dd></dl> <p>Since taxable horsepower was computed based on bore and number of cylinders, not based on actual displacement, it gave rise to engines with "undersquare" dimensions (bore smaller than stroke), which tended to impose an artificially low limit on <a href="/wiki/Rotational_speed" class="mw-redirect" title="Rotational speed">rotational speed</a>, hampering the potential power output and efficiency of the engine. </p><p>The situation persisted for several generations of four- and six-cylinder British engines: For example, <a href="/wiki/Jaguar_Cars" title="Jaguar Cars">Jaguar's</a> 3.4-litre XK engine of the 1950s had six cylinders with a bore of 83 mm (3.27 in) and a stroke of 106 mm (4.17 in),<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> where most American automakers had long since moved to oversquare (large bore, short stroke) <a href="/wiki/V8_engine" title="V8 engine">V8 engines</a>. See, for example, the early <a href="/wiki/Chrysler_Hemi_engine#First_generation:_FirePower" title="Chrysler Hemi engine">Chrysler Hemi engine</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Measurement">Measurement</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=12" title="Edit section: Measurement"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The power of an engine may be measured or estimated at several points in the transmission of the power from its generation to its application. A number of names are used for the power developed at various stages in this process, but none is a clear indicator of either the measurement system or definition used. </p><p>In general: </p> <dl><dd><a href="#Nominal_horsepower">nominal</a> horsepower is derived from the size of the engine and the piston speed and is only accurate at a steam pressure of 48 kPa (7 psi);<sup id="cite_ref-Brown_29-0" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup></dd> <dd><a href="#Indicated_horsepower">indicated</a> or gross horsepower is the theoretical capability of the engine [PLAN/ 33000];</dd> <dd><a href="#Brake_horsepower">brake</a>/net/crankshaft horsepower (power delivered directly to and measured at the engine's crankshaft) equals <dl><dd>indicated horsepower minus frictional losses within the engine (bearing drag, rod and crankshaft windage losses, oil film drag, etc.);</dd></dl></dd> <dd><a href="#Shaft_horsepower">shaft</a> horsepower (power delivered to and measured at the output shaft of the transmission, when present in the system) equals <dl><dd>crankshaft horsepower minus frictional losses in the transmission (bearings, gears, oil drag, windage, etc.);</dd></dl></dd> <dd>effective or true (thp), commonly referred to as wheel horsepower (whp), equals <dl><dd>shaft horsepower minus frictional losses in the universal joint/s, differential, wheel bearings, tire and chain, (if present).</dd></dl></dd></dl> <p>All the above assumes that no power inflation factors have been applied to any of the readings. </p><p>Engine designers use expressions other than horsepower to denote objective targets or performance, such as brake mean effective pressure (BMEP). This is a coefficient of theoretical brake horsepower and cylinder pressures during combustion. </p> <div class="mw-heading mw-heading3"><h3 id="Nominal_horsepower"><span class="anchor" id="nhp"></span><span class="anchor" id="Nominal_horsepower"></span> Nominal horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=13" title="Edit section: Nominal horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Nominal horsepower (nhp) is an early 19th-century <a href="/wiki/Rule_of_thumb" title="Rule of thumb">rule of thumb</a> used to estimate the power of steam engines.<sup id="cite_ref-Brown_29-1" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> It assumed a steam pressure of 7 psi (48 kPa).<sup id="cite_ref-WhitePage520_30-0" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>Nominal horsepower = 7 × area of piston in square inches × equivalent piston speed in feet per minute/33,000. </p><p>For paddle ships, the Admiralty rule was that the piston speed in feet per minute was taken as 129.7 × (stroke)<sup>1/3.38</sup>.<sup id="cite_ref-Brown_29-2" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-WhitePage520_30-1" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> For screw steamers, the intended piston speed was used.<sup id="cite_ref-WhitePage520_30-2" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>The stroke (or length of stroke) was the distance moved by the piston measured in feet. </p><p>For the nominal horsepower to equal the actual power it would be necessary for the mean steam pressure in the cylinder during the stroke to be 7 psi (48 kPa) and for the piston speed to be that generated by the assumed relationship for paddle ships.<sup id="cite_ref-Brown_29-3" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </p><p>The French Navy used the same definition of nominal horse power as the Royal Navy.<sup id="cite_ref-Brown_29-4" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable sortable collapsible"> <tbody><tr> <th colspan="5">Comparison of nominal and indicated horse power </th></tr> <tr> <th>Ship </th> <th>Indicated horse power (ihp) </th> <th>Nominal horse power (nhp) </th> <th>Ratio of ihp to nhp </th> <th>Source </th></tr> <tr valign="top"> <td><a href="/wiki/HMS_Dee_(1832)" title="HMS Dee (1832)"><i>Dee</i></a> </td> <td align="right">272 </td> <td align="right">200 </td> <td align="right">1.36 </td> <td><sup id="cite_ref-Brown_29-5" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/w/index.php?title=HMS_Locust_(1840)&action=edit&redlink=1" class="new" title="HMS Locust (1840) (page does not exist)"><i>Locust</i></a> </td> <td align="right">157 </td> <td align="right">100 </td> <td align="right">1.57 </td> <td><sup id="cite_ref-Brown_29-6" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Rhadamanthus_(1832)" title="HMS Rhadamanthus (1832)"><i>Rhadamanthus</i></a> </td> <td align="right">400 </td> <td align="right">220 </td> <td align="right">1.82 </td> <td><sup id="cite_ref-Brown_29-7" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Albacore_(1856)" class="mw-redirect" title="HMS Albacore (1856)"><i>Albacore</i></a> </td> <td align="right">109 </td> <td align="right">60 </td> <td align="right">1.82 </td> <td><sup id="cite_ref-WhitePage520_30-3" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Porcupine_(1844)" title="HMS Porcupine (1844)"><i>Porcupine</i></a> </td> <td align="right">285 </td> <td align="right">132 </td> <td align="right">2.16 </td> <td><sup id="cite_ref-Brown_29-8" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/w/index.php?title=HMS_Harpy_(1845)&action=edit&redlink=1" class="new" title="HMS Harpy (1845) (page does not exist)"><i>Harpy</i></a> </td> <td align="right">520 </td> <td align="right">200 </td> <td align="right">2.60 </td> <td><sup id="cite_ref-Brown_29-9" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/w/index.php?title=HMS_Spitfire_(1845)&action=edit&redlink=1" class="new" title="HMS Spitfire (1845) (page does not exist)"><i>Spitfire</i></a> </td> <td align="right">380 </td> <td align="right">140 </td> <td align="right">2.70 </td> <td><sup id="cite_ref-Brown_29-10" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/w/index.php?title=HMS_Spiteful_(1842)&action=edit&redlink=1" class="new" title="HMS Spiteful (1842) (page does not exist)"><i>Spiteful</i></a> </td> <td align="right">796 </td> <td align="right">280 </td> <td align="right">2.85 </td> <td><sup id="cite_ref-WhitePage520_30-4" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Jackal_(1844)" title="HMS Jackal (1844)"><i>Jackal</i></a> </td> <td align="right">455 </td> <td align="right">150 </td> <td align="right">3.03 </td> <td><sup id="cite_ref-Brown_29-11" class="reference"><a href="#cite_note-Brown-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/w/index.php?title=HMS_Supply_(1854)&action=edit&redlink=1" class="new" title="HMS Supply (1854) (page does not exist)"><i>Supply</i></a> </td> <td align="right">265 </td> <td align="right">80 </td> <td align="right">3.31 </td> <td><sup id="cite_ref-WhitePage520_30-5" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Simoom_(1849)" title="HMS Simoom (1849)"><i>Simoom</i></a> </td> <td align="right">1,576 </td> <td align="right">400 </td> <td align="right">3.94 </td> <td><sup id="cite_ref-WhitePage520_30-6" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Hector_(1862)" title="HMS Hector (1862)"><i>Hector</i></a> </td> <td align="right">3,256 </td> <td align="right">800 </td> <td align="right">4.07 </td> <td><sup id="cite_ref-WhitePage520_30-7" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Agincourt_(1865)" title="HMS Agincourt (1865)"><i>Agincourt</i></a> </td> <td align="right">6,867 </td> <td align="right">1,350 </td> <td align="right">5.08 </td> <td><sup id="cite_ref-WhitePage520_30-8" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Bellerophon_(1865)" title="HMS Bellerophon (1865)"><i>Bellerophon</i></a> </td> <td align="right">6,521 </td> <td align="right">1,000 </td> <td align="right">6.52 </td> <td><sup id="cite_ref-WhitePage520_30-9" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Monarch_(1868)" title="HMS Monarch (1868)"><i>Monarch</i></a> </td> <td align="right">7,842 </td> <td align="right">1,100 </td> <td align="right">7.13 </td> <td><sup id="cite_ref-WhitePage520_30-10" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> <tr valign="top"> <td><a href="/wiki/HMS_Penelope_(1867)" title="HMS Penelope (1867)"><i>Penelope</i></a> </td> <td align="right">4,703 </td> <td align="right">600 </td> <td align="right">7.84 </td> <td><sup id="cite_ref-WhitePage520_30-11" class="reference"><a href="#cite_note-WhitePage520-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </td></tr> </tbody></table> <div class="mw-heading mw-heading3"><h3 id="Indicated_horsepower"><span class="anchor" id="Indicated_horsepower"></span><span class="anchor" id="ihp"></span> Indicated horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=14" title="Edit section: Indicated horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Indicated horsepower (ihp) is the theoretical power of a reciprocating engine if it is completely frictionless in converting the expanding gas energy (piston pressure × displacement) in the cylinders. It is calculated from the pressures developed in the cylinders, measured by a device called an <i><a href="/wiki/Indicator_diagram" title="Indicator diagram">engine indicator</a></i> – hence indicated horsepower. As the piston advances throughout its stroke, the pressure against the piston generally decreases, and the indicator device usually generates a graph of pressure vs stroke within the working cylinder. From this graph the amount of work performed during the piston stroke may be calculated. </p><p>Indicated horsepower was a better measure of engine power than nominal horsepower (nhp) because it took account of steam pressure. But unlike later measures such as shaft horsepower (shp) and brake horsepower (bhp), it did not take into account power losses due to the machinery internal frictional losses, such as a piston sliding within the cylinder, plus bearing friction, transmission and gear box friction, etc. </p> <div class="mw-heading mw-heading3"><h3 id="Brake_horsepower"><span class="anchor" id="bhp"></span><span class="anchor" id="Brake_horsepower_(bhp)"></span> Brake horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=15" title="Edit section: Brake horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><b>Brake horsepower</b> (<b>bhp</b>) is the power measured using a brake type (load) dynamometer at a specified location, such as the crankshaft, output shaft of the transmission, rear axle or rear wheels.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>In Europe, the <a href="#Deutsches_Institut_für_Normung_70020_(DIN_70020)">DIN 70020</a> standard tests the engine fitted with all ancillaries and the exhaust system as used in the car. The older American standard (<a href="#SAE_gross_power">SAE gross horsepower</a>, referred to as <i>bhp</i>) used an engine without <a href="/wiki/Alternator" title="Alternator">alternator</a>, water pump, and other auxiliary components such as power steering pump, muffled exhaust system, etc., so the figures were higher than the European figures for the same engine. The newer American standard (referred to as <a href="#SAE_net_power">SAE net horsepower</a>) tests an engine with all the auxiliary components (see "Engine power test standards" below).<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> </p><p><i>Brake</i> refers to the device which is used to provide an equal braking force, load to balance, or equal an engine's output force and hold it at a desired rotational speed. During testing, the output torque and rotational speed are measured to determine the brake horsepower. Horsepower was originally measured and calculated by use of the "indicator diagram" (a James Watt invention of the late 18th century), and later by means of a <a href="/wiki/Prony_brake" title="Prony brake">Prony brake</a> connected to the engine's output shaft. Modern <a href="/wiki/Dynamometer" title="Dynamometer">dynamometers</a> use any of several braking methods to measure the engine's brake horsepower, the actual output of the engine itself, before losses to the drivetrain.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Shaft_horsepower">Shaft horsepower</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=16" title="Edit section: Shaft horsepower"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Shaft horsepower (shp) is the power delivered to a propeller shaft, a turbine shaft, or to an output shaft of an automotive transmission.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Shaft horsepower is a common rating for turboshaft and turboprop engines, industrial turbines, and some marine applications. </p><p>Equivalent shaft horsepower (eshp) is sometimes used to rate <a href="/wiki/Turboprop" title="Turboprop">turboprop</a> engines. It includes the equivalent power derived from residual jet thrust from the turbine exhaust.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> 2.5 pounds-force (11 N) of residual jet thrust is estimated to be produced from one unit of horsepower.<sup id="cite_ref-AF1961_34-0" class="reference"><a href="#cite_note-AF1961-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Engine_power_test_standards"><span class="anchor" id="netgross"></span><span class="anchor" id="standards"></span> Engine power test standards</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=17" title="Edit section: Engine power test standards"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There exist a number of different standards determining how the power and torque of an automobile engine is measured and corrected. Correction factors are used to adjust power and torque measurements to standard atmospheric conditions, to provide a more accurate comparison between engines as they are affected by the pressure, humidity, and temperature of ambient air.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> Some standards are described below. </p> <div class="mw-heading mw-heading3"><h3 id="Society_of_Automotive_Engineers/SAE_International"><span id="Society_of_Automotive_Engineers.2FSAE_International"></span><span class="anchor" id="SAE"></span> Society of Automotive Engineers/SAE International</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=18" title="Edit section: Society of Automotive Engineers/SAE International"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Early_"SAE_horsepower""><span id="Early_.22SAE_horsepower.22"></span>Early "SAE horsepower"</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=19" title="Edit section: Early "SAE horsepower""><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For the SAE horsepower formula, see <a href="#RAC_horsepower_(taxable_horsepower)">§ RAC horsepower (taxable horsepower)</a>.</div> <p>In the early twentieth century, a so-called "SAE horsepower" was sometimes quoted for U.S. automobiles. This long predates the <a href="/wiki/Society_of_Automotive_Engineers" class="mw-redirect" title="Society of Automotive Engineers">Society of Automotive Engineers (SAE)</a> horsepower measurement standards and was another name for the industry standard <a href="/wiki/ALAM" class="mw-redirect" title="ALAM">ALAM</a> or <a href="/wiki/National_Automobile_Chamber_of_Commerce" class="mw-redirect" title="National Automobile Chamber of Commerce">NACC</a> horsepower figure and the same as the British RAC horsepower also used for tax purposes. <a href="/wiki/Alliance_of_Automobile_Manufacturers" title="Alliance of Automobile Manufacturers">Alliance for Automotive Innovation</a> is the current successor of ALAM and NACC. </p> <div class="mw-heading mw-heading4"><h4 id="SAE_gross_power"><span class="anchor" id="SAE_gross"></span> SAE gross power</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=20" title="Edit section: SAE gross power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Prior to the 1972 model year, American automakers rated and advertised their engines in brake horsepower, <i><a href="#Brake_horsepower">bhp</a></i>, which was a version of brake horsepower called SAE gross horsepower because it was measured according to Society of Automotive Engineers (SAE) standards (J245 and J1995) that call for a stock test engine without accessories (such as dynamo/alternator, radiator fan, water pump),<sup id="cite_ref-Lucchesi_36-0" class="reference"><a href="#cite_note-Lucchesi-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> and sometimes fitted with long tube test <a href="/wiki/Exhaust_manifold" title="Exhaust manifold">headers</a> in lieu of the <a href="/wiki/Original_equipment_manufacturer" title="Original equipment manufacturer">OEM</a> exhaust manifolds. This contrasts with both SAE net power and <a href="#Deutsches_Institut_für_Normung_70020_(DIN_70020)">DIN 70020</a> standards, which account for engine accessories (but not transmission losses). The atmospheric correction standards for barometric pressure, humidity and temperature for SAE gross power testing were relatively idealistic. </p> <div class="mw-heading mw-heading4"><h4 id="SAE_net_power"><span class="anchor" id="SAE_net"></span> SAE net power</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=21" title="Edit section: SAE net power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the United States, the term <i><a href="#Brake_horsepower">bhp</a></i> fell into disuse in 1971–1972, as automakers began to quote power in terms of SAE net horsepower in accord with SAE standard J1349. Like SAE gross and other brake horsepower protocols, SAE net hp is measured at the engine's crankshaft, and so does not account for transmission losses. However, similar to the <a href="#Deutsches_Institut_für_Normung_70020_(DIN_70020)">DIN 70020</a> standard, SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. This produces ratings in closer alignment with the power produced by the engine as it is actually configured and sold. </p> <div class="mw-heading mw-heading4"><h4 id="SAE_certified_power">SAE certified power</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=22" title="Edit section: SAE certified power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In 2005, the SAE introduced "SAE Certified Power" with SAE J2723.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> To attain certification the test must follow the SAE standard in question, take place in an <a href="/wiki/ISO_9000" class="mw-redirect" title="ISO 9000">ISO 9000</a>/9002 certified facility and be witnessed by an SAE approved third party. </p><p>A few manufacturers such as Honda and Toyota switched to the new ratings immediately.<sup id="cite_ref-JPlungis_38-0" class="reference"><a href="#cite_note-JPlungis-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> The rating for <a href="/wiki/Toyota_Motor_Corporation" class="mw-redirect" title="Toyota Motor Corporation">Toyota's</a> <a href="/wiki/Toyota_Camry" title="Toyota Camry">Camry</a> 3.0 L <i><a href="/wiki/Toyota_MZ_engine#1MZ-FE" title="Toyota MZ engine">1MZ-FE</a></i> V6 fell from 210 to 190 hp (160 to 140 kW).<sup id="cite_ref-JPlungis_38-1" class="reference"><a href="#cite_note-JPlungis-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> The company's Lexus ES 330 and Camry SE V6 (3.3 L V6) were previously rated at 225 hp (168 kW) but the ES 330 dropped to 218 hp (163 kW) while the Camry declined to 210 hp (160 kW). The first engine certified under the new program was the 7.0 L <a href="/wiki/GM_LS_engine#7.0_L" class="mw-redirect" title="GM LS engine">LS7</a> used in the 2006 <a href="/wiki/Chevrolet_Corvette" title="Chevrolet Corvette">Chevrolet Corvette</a> Z06. Certified power rose slightly from 500 to 505 hp (373 to 377 kW). </p><p>While Toyota and Honda are retesting their entire vehicle lineups, other automakers generally are retesting only those with updated powertrains.<sup id="cite_ref-JPlungis_38-2" class="reference"><a href="#cite_note-JPlungis-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> For example, the 2006 Ford Five Hundred is rated at 203 horsepower (151 kW), the same as that of 2005 model. However, the 2006 rating does not reflect the new SAE testing procedure, as Ford did not opt to incur the extra expense of retesting its existing engines.<sup id="cite_ref-JPlungis_38-3" class="reference"><a href="#cite_note-JPlungis-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> Over time, most automakers are expected to comply with the new guidelines. </p><p>SAE tightened its horsepower rules to eliminate the opportunity for engine manufacturers to manipulate factors affecting performance such as how much oil was in the crankcase, engine control system calibration, and whether an engine was tested with high octane fuel. In some cases, such can add up to a change in horsepower ratings. </p> <div class="mw-heading mw-heading3"><h3 id="Deutsches_Institut_für_Normung_70020_(DIN_70020)"><span id="Deutsches_Institut_f.C3.BCr_Normung_70020_.28DIN_70020.29"></span><span class="anchor" id="DIN"></span><span class="anchor" id="70020"></span><i>Deutsches Institut für Normung</i> 70020 (DIN 70020)</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=23" title="Edit section: Deutsches Institut für Normung 70020 (DIN 70020)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>DIN 70020 is a German <a href="/wiki/DIN" class="mw-redirect" title="DIN">DIN</a> standard for measuring road vehicle horsepower. DIN hp is measured at the engine's output shaft as a form of <a href="#Metric_horsepower">metric horsepower</a> rather than <a href="#Mechanical_horsepower">mechanical horsepower</a>. Similar to <a href="#SAE_gross_power">SAE net power</a> rating, and unlike <a href="#SAE_gross_power">SAE gross power</a>, DIN testing measures the engine as installed in the vehicle, with cooling system, charging system and stock exhaust system all connected. DIN hp is often abbreviated as "<a href="#Metric_horsepower">PS</a>", derived from the German word <i><b>Pferdestärke</b></i> (literally, "horsepower"). </p> <div class="mw-heading mw-heading3"><h3 id="CUNA">CUNA</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=24" title="Edit section: CUNA"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A test standard by <a href="/wiki/Italy" title="Italy">Italian</a> CUNA (<i>Commissione Tecnica per l'Unificazione nell'Automobile</i>, Technical Commission for Automobile Unification), a federated entity of <a href="/wiki/Standards_organisation" class="mw-redirect" title="Standards organisation">standards organisation</a> <a href="/wiki/Ente_Nazionale_Italiano_di_Unificazione" title="Ente Nazionale Italiano di Unificazione">UNI</a>, was formerly used in Italy. CUNA prescribed that the engine be tested with all accessories necessary to its running fitted (such as the water pump), while all others – such as alternator/dynamo, radiator fan, and exhaust manifold – could be omitted.<sup id="cite_ref-Lucchesi_36-1" class="reference"><a href="#cite_note-Lucchesi-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> All calibration and accessories had to be as on production engines.<sup id="cite_ref-Lucchesi_36-2" class="reference"><a href="#cite_note-Lucchesi-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Economic_Commission_for_Europe_R24"><span class="anchor" id="ECE_R24"></span>Economic Commission for Europe R24</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=25" title="Edit section: Economic Commission for Europe R24"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>ECE R24 is a <a href="/wiki/UNECE_Regulations" class="mw-redirect" title="UNECE Regulations">UN standard</a> for the approval of compression ignition engine emissions, installation and measurement of engine power.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> It is similar to DIN 70020 standard, but with different requirements for connecting an engine's fan during testing causing it to absorb less power from the engine.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Economic_Commission_for_Europe_R85"><span class="anchor" id="ECE_R85"></span>Economic Commission for Europe R85</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=26" title="Edit section: Economic Commission for Europe R85"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>ECE R85 is a <a href="/wiki/UNECE_Regulations" class="mw-redirect" title="UNECE Regulations">UN standard</a> for the approval of internal combustion engines with regard to the measurement of the net power.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="80/1269/EEC"><span id="80.2F1269.2FEEC"></span>80/1269/EEC</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=27" title="Edit section: 80/1269/EEC"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Directive_80/1269/EEC" title="Directive 80/1269/EEC">80/1269/EEC</a> of 16 December 1980 is a European Union standard for road vehicle engine power. </p> <div class="mw-heading mw-heading3"><h3 id="International_Organization_for_Standardization"><span class="anchor" id="ISO"></span>International Organization for Standardization</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=28" title="Edit section: International Organization for Standardization"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">International Organization for Standardization</a> (ISO) publishes several standards for measuring engine horsepower. </p> <ul><li><a href="/wiki/ISO_14396" class="mw-redirect" title="ISO 14396">ISO 14396</a> specifies the additional and method requirement for determining the power of reciprocating internal combustion engines when presented for an <a href="/wiki/ISO_8178" title="ISO 8178">ISO 8178</a> exhaust emission test. It applies to reciprocating internal combustion engines for land, rail and marine use excluding engines of motor vehicles primarily designed for road use.<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup></li> <li><a href="/w/index.php?title=ISO_1585&action=edit&redlink=1" class="new" title="ISO 1585 (page does not exist)">ISO 1585</a> is an engine net power test code intended for road vehicles.<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup></li> <li><a href="/w/index.php?title=ISO_2534&action=edit&redlink=1" class="new" title="ISO 2534 (page does not exist)">ISO 2534</a> is an engine gross power test code intended for road vehicles.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup></li> <li><a href="/w/index.php?title=ISO_4164&action=edit&redlink=1" class="new" title="ISO 4164 (page does not exist)">ISO 4164</a> is an engine net power test code intended for mopeds.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup></li> <li><a href="/w/index.php?title=ISO_4106&action=edit&redlink=1" class="new" title="ISO 4106 (page does not exist)">ISO 4106</a> is an engine net power test code intended for motorcycles.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup></li> <li><a href="/w/index.php?title=ISO_9249&action=edit&redlink=1" class="new" title="ISO 9249 (page does not exist)">ISO 9249</a> is an engine net power test code intended for earth moving machines.<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Japanese_Industrial_Standard_D_1001"><span class="anchor" id="Japan"></span><span class="anchor" id="JIS"></span>Japanese Industrial Standard D 1001</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=29" title="Edit section: Japanese Industrial Standard D 1001"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>JIS D 1001 is a Japanese net, and gross, engine power test code for <a href="/wiki/Automobile" class="mw-redirect" title="Automobile">automobiles</a> or <a href="/wiki/Truck" title="Truck">trucks</a> having a spark ignition, <a href="/wiki/Diesel_engine" title="Diesel engine">diesel engine</a>, or fuel injection engine.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=30" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Brake-specific_fuel_consumption" title="Brake-specific fuel consumption">Brake-specific fuel consumption</a> – how much fuel an engine consumes per unit energy output</li> <li><a href="/wiki/Dynamometer#How_dynamometers_are_used_for_engine_testing" title="Dynamometer">Dynamometer engine testing</a></li> <li><a href="/wiki/European_units_of_measurement_directives" title="European units of measurement directives">European units of measurement directives</a></li> <li><a href="/wiki/Horsepower-hour" title="Horsepower-hour">Horsepower-hour</a></li> <li><a href="/wiki/Mean_effective_pressure" title="Mean effective pressure">Mean effective pressure</a></li> <li><a href="/wiki/Torque" title="Torque">Torque</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=31" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.britannica.com/EBchecked/topic/272384/horsepower">"Horsepower"</a>, <i>Encyclopædia Britannica Online</i>. Retrieved 2012-06-24.</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.britannica.com/EBchecked/topic/291305/International-System-of-Units-SI">"International System of Units" (SI)</a>, <i>Encyclopædia Britannica Online</i>. 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Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Certified+Power+-+SAE+J1349+Certified+Power+SAE+International&rft.pub=Sae.org&rft_id=http%3A%2F%2Fwww.sae.org%2Fcertifiedpower%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-JPlungis-38"><span class="mw-cite-backlink">^ <a href="#cite_ref-JPlungis_38-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-JPlungis_38-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-JPlungis_38-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-JPlungis_38-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">Jeff Plungis, <i>Asians Oversell Horsepower</i>, Detroit News</span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r024r2e.pdf">"Text of the 1958 Agreement, ECE Regulation 24, Revision 2, Annex 10"</a> <span class="cs1-format">(PDF)</span>. <i>www.unece.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.unece.org&rft.atitle=Text+of+the+1958+Agreement%2C+ECE+Regulation+24%2C+Revision+2%2C+Annex+10&rft_id=http%3A%2F%2Fwww.unece.org%2Ffileadmin%2FDAM%2Ftrans%2Fmain%2Fwp29%2Fwp29regs%2Fr024r2e.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBreen2003" class="citation web cs1">Breen, Jim (2003-03-22). <a rel="nofollow" class="external text" href="https://archive.today/20030406025121/http://www.farmersjournal.ie/2003/0322/farmmanagement/machinery/tractor.htm">"Tractor and machine comparison: what's the 'true' measure"</a>. Irish Farmers Journal. Archived from <a rel="nofollow" class="external text" href="http://www.farmersjournal.ie/2003/0322/farmmanagement/machinery/tractor.htm">the original</a> on 2003-04-06.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Tractor+and+machine+comparison%3A+what%27s+the+%27true%27+measure&rft.pub=Irish+Farmers+Journal&rft.date=2003-03-22&rft.aulast=Breen&rft.aufirst=Jim&rft_id=http%3A%2F%2Fwww.farmersjournal.ie%2F2003%2F0322%2Ffarmmanagement%2Fmachinery%2Ftractor.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://live.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r085e.pdf">"ECE Regulation 85"</a> <span class="cs1-format">(PDF)</span><span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ECE+Regulation+85&rft_id=http%3A%2F%2Flive.unece.org%2Ffileadmin%2FDAM%2Ftrans%2Fmain%2Fwp29%2Fwp29regs%2Fr085e.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/catalogue_detail.htm?csnumber=32909">"ISO 14396:2002 - Reciprocating internal combustion engines - Determination and method for the measurement of engine power - Additional requirements for exhaust emission tests in accordance with ISO 8178"</a>. Iso.org. 2007-09-30<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+14396%3A2002+-+Reciprocating+internal+combustion+engines+-+Determination+and+method+for+the+measurement+of+engine+power+-+Additional+requirements+for+exhaust+emission+tests+in+accordance+with+ISO+8178&rft.pub=Iso.org&rft.date=2007-09-30&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fcatalogue_detail.htm%3Fcsnumber%3D32909&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/catalogue_detail.htm?csnumber=6179">"ISO 1585:1992 - Road vehicles - Engine test code - Net power"</a>. Iso.org. 1999-11-15<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+1585%3A1992+-+Road+vehicles+-+Engine+test+code+-+Net+power&rft.pub=Iso.org&rft.date=1999-11-15&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fcatalogue_detail.htm%3Fcsnumber%3D6179&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=7476">"ISO 2534:1998 - Road vehicles - Engine test code - Gross power"</a>. Iso.org. 2009-03-31<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+2534%3A1998+-+Road+vehicles+-+Engine+test+code+-+Gross+power&rft.pub=Iso.org&rft.date=2009-03-31&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fiso_catalogue%2Fcatalogue_tc%2Fcatalogue_detail.htm%3Fcsnumber%3D7476&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-45">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=9932">"ISO 4164:1978 - Road vehicles - Mopeds - Engine test code - Net power"</a>. Iso.org. 2009-10-07<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+4164%3A1978+-+Road+vehicles+-+Mopeds+-+Engine+test+code+-+Net+power&rft.pub=Iso.org&rft.date=2009-10-07&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fiso_catalogue%2Fcatalogue_tc%2Fcatalogue_detail.htm%3Fcsnumber%3D9932&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=31406">"ISO 4106:2004 - Motorcycles - Engine test code - Net power"</a>. Iso.org. 2009-06-26<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+4106%3A2004+-+Motorcycles+-+Engine+test+code+-+Net+power&rft.pub=Iso.org&rft.date=2009-06-26&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fiso_catalogue%2Fcatalogue_tc%2Fcatalogue_detail.htm%3Fcsnumber%3D31406&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=38008">"ISO 9249:2007 - Earth-moving machinery - Engine test code - Net power"</a>. Iso.org. 2011-03-17<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ISO+9249%3A2007+-+Earth-moving+machinery+-+Engine+test+code+-+Net+power&rft.pub=Iso.org&rft.date=2011-03-17&rft_id=http%3A%2F%2Fwww.iso.org%2Fiso%2Fiso_catalogue%2Fcatalogue_tc%2Fcatalogue_detail.htm%3Fcsnumber%3D38008&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> <li id="cite_note-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-48">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110722121539/http://www.webstore.jsa.or.jp/webstore/Com/FlowControl.jsp?lang=en&bunsyoId=JIS+D+1001:1993&dantaiCd=JIS&status=1&pageNo=0">"JSA Web Store - JIS D 1001:1993 Road vehicles - Engine power test code"</a>. Webstore.jsa.or.jp. Archived from <a rel="nofollow" class="external text" href="http://www.webstore.jsa.or.jp/webstore/Com/FlowControl.jsp?lang=en&bunsyoId=JIS+D+1001%3A1993&dantaiCd=JIS&status=1&pageNo=0">the original</a> on 2011-07-22<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=JSA+Web+Store+-+JIS+D+1001%3A1993+Road+vehicles+-+Engine+power+test+code&rft.pub=Webstore.jsa.or.jp&rft_id=http%3A%2F%2Fwww.webstore.jsa.or.jp%2Fwebstore%2FCom%2FFlowControl.jsp%3Flang%3Den%26bunsyoId%3DJIS%2BD%2B1001%253A1993%26dantaiCd%3DJIS%26status%3D1%26pageNo%3D0&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHorsepower" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Horsepower&action=edit&section=32" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 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.navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Imperial_units" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Imperial_units" title="Template:Imperial units"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Imperial_units" title="Template talk:Imperial units"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Imperial_units" title="Special:EditPage/Template:Imperial units"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Imperial_units" style="font-size:114%;margin:0 4em"><a href="/wiki/Imperial_units" title="Imperial units">Imperial units</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="/wiki/Comparison_of_the_imperial_and_US_customary_measurement_systems" title="Comparison of the imperial and US customary measurement systems">Comparison with US customary system</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Length</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Twip" title="Twip">Twip</a></li> <li><a href="/wiki/Thousandth_of_an_inch" title="Thousandth of an inch">Thousandth of an inch</a></li> <li><a href="/wiki/Barleycorn_(unit)" title="Barleycorn (unit)">Barleycorn</a></li> <li><a href="/wiki/Inch" title="Inch">Inch</a></li> <li><a href="/wiki/Hand_(unit)" title="Hand (unit)">Hand</a></li> <li><a href="/wiki/Link_(unit)" title="Link (unit)">Link</a></li> <li><a href="/wiki/Foot_(unit)" title="Foot (unit)">Foot</a></li> <li><a href="/wiki/Yard" title="Yard">Yard</a></li> <li><a href="/wiki/Fathom" title="Fathom">Fathom</a></li> <li><a href="/wiki/Rod_(unit)" title="Rod (unit)">Rod</a></li> <li><a href="/wiki/Chain_(unit)" title="Chain (unit)">Chain</a></li> <li><a href="/wiki/Gunter%27s_chain" title="Gunter's chain">Gunter's chain</a></li> <li><a href="/wiki/Furlong" title="Furlong">Furlong</a></li> <li><a href="/wiki/Cable_length" title="Cable length">Cable</a></li> <li><a href="/wiki/Mile" title="Mile">Mile</a></li> <li><a href="/wiki/Nautical_mile" title="Nautical mile">Nautical mile</a></li> <li><a href="/wiki/League_(unit)" title="League (unit)">League</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Area</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Square_inch" title="Square inch">Square inch</a></li> <li><a href="/wiki/Square_foot" title="Square foot">Square foot</a></li> <li><a href="/wiki/Square_yard" title="Square yard">Square yard</a></li> <li><a href="/wiki/Perch_(area)" class="mw-redirect" title="Perch (area)">Perch</a></li> <li><a href="/wiki/Rood_(unit)" title="Rood (unit)">Rood</a></li> <li><a href="/wiki/Acre" title="Acre">Acre</a></li> <li><a href="/wiki/Square_mile" title="Square mile">Square mile</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Volume</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Derived</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cubic_inch" title="Cubic inch">Cubic inch</a></li> <li><a href="/wiki/Cubic_foot" title="Cubic foot">Cubic foot</a></li> <li><a href="/wiki/Hoppus" title="Hoppus">Hoppus</a></li> <li><a href="/wiki/Cubic_yard" title="Cubic yard">Cubic yard</a></li> <li><a href="/wiki/Cubic_mile" title="Cubic mile">Cubic mile</a></li> <li><a href="/wiki/Tmcft" title="Tmcft">Tmcft</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Cooking</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Teaspoon" title="Teaspoon">Teaspoon</a></li> <li><a href="/wiki/Tablespoon" title="Tablespoon">Tablespoon</a></li> <li><a href="/wiki/Fluid_ounce" title="Fluid ounce">Fluid ounce</a></li> <li><a href="/wiki/Cup_(unit)" title="Cup (unit)">Cup</a></li> <li><a href="/wiki/Pint" title="Pint">Pint</a></li> <li><a href="/wiki/Quart" title="Quart">Quart</a></li> <li><a href="/wiki/Trade_gallon" title="Trade gallon">Trade gallon</a></li> <li><a href="/wiki/Gallon" title="Gallon">Gallon</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chaldron" title="Chaldron">Chaldron</a></li> <li><a href="/wiki/Minim_(unit)" title="Minim (unit)">Minim</a></li> <li><a href="/wiki/Gill_(unit)" title="Gill (unit)">Gill</a></li> <li><a href="/wiki/Scruple_(unit)" title="Scruple (unit)">Fluid Scruple</a></li> <li><a href="/wiki/Dram_(unit)" title="Dram (unit)">Fluid Drachm</a></li> <li><a href="/wiki/Peck" title="Peck">Peck</a></li> <li><a href="/wiki/Bushel" title="Bushel">Bushel</a></li> <li><a href="/wiki/Barrel_(unit)" title="Barrel (unit)">Barrel</a></li> <li><a href="/wiki/Stuck_(unit)" title="Stuck (unit)">Stuck</a></li> <li><a href="/wiki/Hogshead" title="Hogshead">Hogshead</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Speed</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Miles_per_hour" title="Miles per hour">Miles per hour</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mass</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Grain_(unit)" title="Grain (unit)">Grain</a></li> <li><a href="/wiki/Dram_(unit)" title="Dram (unit)">Drachm</a></li> <li><a href="/wiki/Ounce" title="Ounce">Ounce</a></li> <li><a href="/wiki/Pound_(mass)" title="Pound (mass)">Pound (mass)</a></li> <li><a href="/wiki/Stone_(unit)" title="Stone (unit)">Stone</a></li> <li><a href="/wiki/Quarter_(unit)" title="Quarter (unit)">Quarter</a></li> <li><a href="/wiki/Slug_(unit)" title="Slug (unit)">Slug</a></li> <li><a href="/wiki/Long_hundred" title="Long hundred">Long hundred</a></li> <li><a href="/wiki/Hundredweight" title="Hundredweight">Hundredweight</a></li> <li><a href="/wiki/Ship_load" title="Ship load">Ship load</a></li> <li><a href="/wiki/Long_Ton" class="mw-redirect" title="Long Ton">Ton</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Pressure</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ksi_(unit)" class="mw-redirect" title="Ksi (unit)">Ksi</a></li> <li><a href="/wiki/Pounds_per_square_inch" class="mw-redirect" title="Pounds per square inch">Pounds per square inch</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other units and measures</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/British_thermal_unit" title="British thermal unit">British thermal unit</a></li> <li><a href="/wiki/Degree_(angle)" title="Degree (angle)">Degree</a></li> <li><a href="/wiki/Fahrenheit" title="Fahrenheit">Fahrenheit</a></li> <li><a href="/wiki/Rankine_scale" title="Rankine scale">Rankine</a></li> <li><a href="/wiki/Foot-candle" title="Foot-candle">Foot-candle</a></li> <li><a href="/wiki/Foot-pound_(energy)" title="Foot-pound (energy)">Foot-pound</a></li> <li><a href="/wiki/Foot-poundal" title="Foot-poundal">Foot-poundal</a></li> <li><a class="mw-selflink selflink">Horsepower</a></li> <li><a href="/wiki/Horsepower-hour" title="Horsepower-hour">Horsepower-hour</a></li> <li><a href="/wiki/Kenning_(unit)" class="mw-redirect" title="Kenning (unit)">Kenning</a></li> <li><a href="/wiki/Pound_(force)" title="Pound (force)">Pound (force)</a></li> <li><a href="/wiki/Pound-foot_(torque)" title="Pound-foot (torque)">Pound-foot</a></li> <li><a href="/wiki/Poundal" title="Poundal">Poundal</a></li> <li><a href="/wiki/Span_(unit)" title="Span (unit)">Span</a></li> <li><a href="/wiki/Spinning_count" title="Spinning count">Spinning count</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related systems</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Avoirdupois_system" class="mw-redirect" title="Avoirdupois system">Avoirdupois system</a></li> <li><a href="/wiki/English_units" title="English units">English units</a> <ul><li><a href="/wiki/Winchester_measure" title="Winchester measure">Winchester</a></li> <li><a href="/wiki/Exchequer_Standards" title="Exchequer Standards">Exchequer</a></li></ul></li> <li><a href="/wiki/English_Engineering_units" class="mw-redirect" title="English Engineering units">English Engineering units</a></li> <li><a href="/wiki/Foot%E2%80%93pound%E2%80%93second_system" class="mw-redirect" title="Foot–pound–second system">Foot–pound–second system (FPS)</a></li> <li><a href="/wiki/Twenty-foot_equivalent_unit" title="Twenty-foot equivalent unit">Twenty-foot equivalent unit</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="United_States_customary_units" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:United_States_Customary_Units" title="Template:United States Customary Units"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:United_States_Customary_Units" title="Template talk:United States Customary Units"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:United_States_Customary_Units" title="Special:EditPage/Template:United States Customary Units"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="United_States_customary_units" style="font-size:114%;margin:0 4em"><a href="/wiki/United_States_customary_units" title="United States customary units">United States customary units</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="/wiki/Comparison_of_the_imperial_and_US_customary_measurement_systems" title="Comparison of the imperial and US customary measurement systems">Comparison with imperial unit system</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Length</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Thousandth_of_an_inch" title="Thousandth of an inch">Thousandth of an inch</a></li> <li><a href="/wiki/Inch" title="Inch">Inch</a></li> <li><a href="/wiki/Hand_(unit)" title="Hand (unit)">Hand</a></li> <li><a href="/wiki/Link_(unit)" title="Link (unit)">Link</a></li> <li><a href="/wiki/Foot_(unit)" title="Foot (unit)">Foot</a></li> <li><a href="/wiki/Yard" title="Yard">Yard</a></li> <li><a href="/wiki/Rod_(unit)" title="Rod (unit)">Rod</a></li> <li><a href="/wiki/Chain_(unit)" title="Chain (unit)">Chain</a></li> <li><a href="/wiki/Furlong" title="Furlong">Furlong</a></li> <li><a href="/wiki/Mile" title="Mile">Mile</a> <ul><li><a href="/wiki/Statute_mile" class="mw-redirect" title="Statute mile">statute</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Area</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Square_inch" title="Square inch">Square inch</a></li> <li><a href="/wiki/Square_foot" title="Square foot">Square foot</a></li> <li><a href="/wiki/Square_yard" title="Square yard">Square yard</a></li> <li><a href="/wiki/Acre" title="Acre">Acre</a></li> <li><a href="/wiki/Square_mile" title="Square mile">Square mile</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Volume</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Derived</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cubic_inch" title="Cubic inch">Cubic inch</a></li> <li><a href="/wiki/Cubic_foot" title="Cubic foot">Cubic foot</a></li> <li><a href="/wiki/Cubic_yard" title="Cubic yard">Cubic yard</a></li> <li><a href="/wiki/Cubic_mile" title="Cubic mile">Cubic mile</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Cooking</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Teaspoon" title="Teaspoon">Teaspoon</a></li> <li><a href="/wiki/Tablespoon" title="Tablespoon">Tablespoon</a></li> <li><a href="/wiki/Fluid_ounce" title="Fluid ounce">Fluid ounce</a></li> <li><a href="/wiki/Cup_(unit)" title="Cup (unit)">Cup</a></li> <li><a href="/wiki/Pint" title="Pint">Pint</a></li> <li><a href="/wiki/Quart" title="Quart">Quart</a></li> <li><a href="/wiki/Gallon" title="Gallon">Gallon</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Wood</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Board_foot" title="Board foot">Board foot</a></li> <li><a href="/wiki/Cord_(unit)" title="Cord (unit)">Cord</a></li> <li><a href="/wiki/Face_cord" title="Face cord">Face cord</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Minim_(unit)" title="Minim (unit)">Minim</a></li> <li><a href="/wiki/Gill_(unit)" title="Gill (unit)">Gill</a></li> <li><a href="/wiki/Peck" title="Peck">Peck</a></li> <li><a href="/wiki/Bushel" title="Bushel">Bushel</a></li> <li><a href="/wiki/Barrel_(unit)" title="Barrel (unit)">Barrel</a></li> <li><a href="/wiki/Acre-foot" title="Acre-foot">Acre-foot</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Speed</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Feet_per_second" class="mw-redirect" title="Feet per second">Feet per second</a></li> <li><a href="/wiki/Miles_per_hour" title="Miles per hour">Miles per hour</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mass</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Grain_(unit)" title="Grain (unit)">Grain</a></li> <li><a href="/wiki/Dram_(unit)" title="Dram (unit)">Dram</a></li> <li><a href="/wiki/Ounce" title="Ounce">Ounce</a></li> <li><a href="/wiki/Pound_(mass)" title="Pound (mass)">Pound</a></li> <li><a href="/wiki/Hundredweight" title="Hundredweight">Hundredweight</a></li> <li><a href="/wiki/Ton" title="Ton">Ton</a> <ul><li><a href="/wiki/Long_ton" title="Long ton">Long</a></li> <li><a href="/wiki/Short_ton" title="Short ton">Short</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Force</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Poundal" title="Poundal">Poundal</a></li> <li><a href="/wiki/Pound_(force)" title="Pound (force)">Pound-force</a></li> <li><a href="/wiki/Kip_(unit)" title="Kip (unit)">Kip</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Pressure</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Inch_of_mercury" title="Inch of mercury">Inch of mercury</a></li> <li><a href="/wiki/Pounds_per_square_inch" class="mw-redirect" title="Pounds per square inch">Pounds per square inch</a></li> <li><a href="/wiki/Ksi_(unit)" class="mw-redirect" title="Ksi (unit)">Kilopounds per square inch</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other units and measures</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bolt_(cloth)" title="Bolt (cloth)">Bolt (cloth)</a></li> <li><a href="/wiki/British_thermal_unit" title="British thermal unit">British thermal unit</a></li> <li><a href="/wiki/Degree_(angle)" title="Degree (angle)">Degree (angle)</a></li> <li><a href="/wiki/Fahrenheit" title="Fahrenheit">Fahrenheit</a></li> <li><a href="/wiki/Foot-candle" title="Foot-candle">Foot-candle</a></li> <li><a href="/wiki/Foot-lambert" title="Foot-lambert">Foot-lambert</a></li> <li><a href="/wiki/Foot-pound_(energy)" title="Foot-pound (energy)">Foot-pound (energy)</a></li> <li><a class="mw-selflink selflink">Horsepower</a></li> <li><a href="/wiki/Perm_(unit)" title="Perm (unit)">Perm</a></li> <li><a href="/wiki/Pound-foot_(torque)" title="Pound-foot (torque)">Pound-foot (torque)</a></li> <li><a href="/wiki/Spinning_count" title="Spinning count">Spinning count</a></li> <li><a href="/wiki/Ton_of_refrigeration" title="Ton of refrigeration">Ton of refrigeration</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related systems</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/American_wire_gauge" title="American wire gauge">American wire gauge</a></li> <li><a href="/wiki/Avoirdupois_system" class="mw-redirect" title="Avoirdupois system">Avoirdupois system</a></li> <li><a href="/wiki/Body_jewelry_sizes" title="Body jewelry sizes">Body jewelry sizes</a></li> <li><a href="/wiki/English_Engineering_Units" title="English Engineering Units">English Engineering Units</a></li> <li><a href="/wiki/Foot%E2%80%93pound%E2%80%93second_system_of_units" title="Foot–pound–second system of units">Foot–pound–second system of units</a></li></ul> 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