Convert Horsepower to Kilowatt

One mechanical horsepower equals exactly 745.69987 watts, or 0.74569987 kilowatts. This is the definition used in the United States for engines: car engines, electric motors listed on American nameplates and pump ratings. Multiplying horsepower by 0.7457 (rounded) gives kilowatts. A 200 hp engine produces 149.14 kW; a 500 hp engine produces 372.85 kW.

The gotcha with horsepower is that there are two common definitions and they are not equal. Mechanical (or imperial) hp is 745.7 W. Metric horsepower — called Pferdestärke (PS) in German, or CV in French and Spanish — is defined as the power needed to lift 75 kg by 1 metre in 1 second, which works out to 735.499 W. The difference is about 1.4%: a car rated at 200 PS produces 147.1 kW, not 149.1 kW. German and Italian car brochures quote PS; American brochures quote hp. When comparing a BMW's 306 PS to a Ford's 300 hp, the BMW has 225.1 kW and the Ford has 223.7 kW — they are closer than the badge numbers suggest.

Electric vehicles have largely shifted the conversation to kilowatts and kilowatt-hours directly. A Tesla Model 3 Long Range is rated at 358 hp (or 267 kW) in the US; the same car's European spec sheet shows 283 kW, partly because of different test protocols and partly to avoid the PS-vs-hp ambiguity altogether. The shift to kW as the primary unit for EV motors makes the hp conversion a bridge to familiarity for buyers accustomed to the old metric.

Industrial motors, generators and pumps are also routinely rated in both units. A 50 hp pump motor is 37.3 kW; a 100 kW generator is 134.1 hp. Electrical engineers work in watts and kilowatts; mechanical engineers in legacy industries still reach for horsepower — knowing the factor lets both groups read the same nameplate.