kW to HP Converter: Mechanical and Metric Horsepower
Convert kilowatts to mechanical horsepower and metric horsepower (PS), or back to watts and kW. Uses 1 hp = 745.7 W and 1 PS = 735.5 W, with a table of common engine ratings.
Type a power to see it in W, kW, hp and PS.
Results are at the crankshaft. Wheel horsepower is lower because the gearbox, driveshaft and tyres lose some power on the way.
| Torque unit | Power unit | Crossover |
|---|---|---|
| lb·ft | hp | 5,252.11312203 rpm |
| N·m | PS | 7,023.49570202 rpm |
| N·m | kW | 9,549.29658551 rpm |
About the kW to HP Converter
The kW to HP Converter turns kilowatts into horsepower. Type a power and the converter shows it in mechanical horsepower (hp), metric horsepower (PS), kilowatts and watts at once. The page opens with kilowatts as the input unit, so typing an engine's kW rating gives its horsepower straight away. Pick another unit to go the other way, from hp or PS back to kW.
Car makers in Europe and Asia quote engine power in kW or PS, while the United States and the United Kingdom still use hp. The two horsepowers are close but not the same: a 100 kW engine is 134.1 hp but 136.0 PS. Results are at the crankshaft; power at the wheels is lower because the drivetrain loses some of it.
The conversion factors
Mechanical horsepower is defined as 550 foot-pounds-force per second, which works out to 745.69987158227022 W. Metric horsepower, written PS from the German Pferdestärke and also called cv or ch, is 75 kilogram-force metres per second, exactly 735.49875 W. To convert:
A rough rule of thumb is hp ≈ kW × 1.341 and PS ≈ kW × 1.36.
Worked examples
100 kW
100,000 ÷ 745.69987 = 134.10220896 hp, and 100,000 ÷ 735.49875 = 135.96216173 PS.
300 hp to kW
300 × 745.69987 W = 223,709.96 W, which is 223.709961475 kW.
A 150 PS hatchback
150 × 735.49875 = 110,324.8 W, so the engine is 110.3 kW or 147.9 hp.
Common engine ratings
50 kW is 67.1 hp (68.0 PS), 75 kW is 100.6 hp (102.0 PS), 110 kW is 147.5 hp (149.6 PS), 150 kW is 201.2 hp (203.9 PS), 200 kW is 268.2 hp (271.9 PS) and 300 kW is 402.3 hp (407.9 PS).
Which horsepower should I use?
Use mechanical horsepower, hp, when you compare cars sold in the United States or the United Kingdom, or when a spec sheet says bhp. Use PS when a European, Japanese or Korean brochure gives the power as PS, cv or ch. The kilowatt figure is the legal unit in the European Union, so it is printed on registration documents and type approval papers. When two sources disagree by about 1.4 percent, one of them is almost certainly quoting PS and the other hp.
Electric motors and boilers
Electric motor nameplates give output power in kW in most of the world and in hp in North America; the same factor of 745.7 W applies. Boiler horsepower is a different unit, about 9.81 kW, and is not used here.
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Related tools
Work out horsepower from torque and engine speed with the full Horsepower Calculator, or convert electrical power between amps and watts with the Amps to Watts Calculator.
Frequently asked questions
How do I convert kW to hp?
Divide the power in watts by 745.7, or multiply the kilowatts by about 1.341. A 100 kW engine is about 134.1 mechanical horsepower.
How do I convert kW to PS?
Divide the power in watts by 735.49875, or multiply the kilowatts by about 1.36. A 100 kW engine is about 136.0 PS, slightly more than its figure in hp.
How do I convert hp to kW?
Multiply the horsepower by 0.7457. A 300 hp engine is about 223.7 kW. Choose hp as the input unit in the converter to see every unit at once.
Why do car brochures show different horsepower figures?
Some markets quote mechanical horsepower and others metric horsepower, PS. The same engine can be listed as 148 hp in one country and 150 PS in another without any change in power.
Is kW to hp the same for electric motors?
Yes. A motor's output in kW converts to hp with the same factor of 745.7 W per hp. Do not use it for boiler horsepower, which is a different unit of about 9.81 kW.