Horsepower to Watts Converter
Convert mechanical (imperial) horsepower to watts. 1 hp = 745.7 W.
Result
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How to use this calculator
- Enter horsepower.
- Pick HP type (mechanical for US cars, metric for Euro cars, electrical for motor specs).
- Read watts and kW.
About this calculator
"Horsepower" actually has three definitions used in different contexts. Mechanical (or imperial) is 745.7 W — used for cars in the US. Metric (PS, Pferdestärke, used in Europe) is 735.5 W. Electrical is exactly 746 W — used by motor manufacturers. The differences are small (<2%) but matter for precise conversions.
Frequently asked
Why are there multiple horsepower units?+
Historical accident. Watt defined his 1 hp ≈ 33,000 ft-lbf/min (mechanical). Metric horsepower came from continental Europe at 75 m·kgf/s. Electrical horsepower was rounded for motor specifications.
Which is used for cars?+
US: mechanical hp. Europe: metric (often called "PS" or "BHP"). Watch for "BHP" specifically — same as mechanical hp.
Is "horsepower" a force or a power?+
Power — energy per time. Watt is the SI unit (1 J/s).
What about "boiler horsepower"?+
Yet another definition (9809 W) used in steam-heating systems. Different from any of the three above.
How accurate is the 1 hp ≈ 0.75 kW shortcut?+
Within 1.5% — fine for back-of-envelope. For precise conversion, use the calculator.
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