How to convert kW to hp
The kilowatt (kW) is the SI unit of power. Horsepower comes in two versions that differ by about 1.4%, so first check which one your figure uses.
- Mechanical horsepower (hp), used in the US and the UK, is 550 foot-pounds per second, or 745.699872 W.
- Metric horsepower is 75 kilogram-force meters per second, exactly 735.49875 W. It is written PS in German, CV in Italian and Spanish, ch in French and pk in Dutch.
hp = kW ÷ 0.745699872
kW = hp × 0.745699872
PS = kW ÷ 0.73549875
1 hp = 1.01387 PS, 1 PS = 0.98632 hpWorked examples
- 100 kW ÷ 0.745699872 = 134.10 hp, or 135.96 PS.
- 300 hp × 0.745699872 = 223.71 kW.
- 150 PS is 110.32 kW, which is 147.95 hp.
A quick check: kW × 1.34 gives hp, and hp × 0.75 gives kW.
Why car power figures do not match
European brochures often give power in kW with PS in brackets, while US brochures give hp. Because PS is slightly smaller than hp, the same engine shows a bigger number in PS: 300 hp is 304.2 PS. If a figure looks about 1.4% off, the two sources are probably using different horsepower.
Registration papers in many countries give power in kW only, and electric motors and chargers are rated in kW too. The watt field is there for small motors and electrical loads: 1 kW is 1,000 W.
Crank, wheel and unit
Converting units does not move the point where power was measured. A rated engine figure is usually measured at the crankshaft, while a chassis dyno measures at the wheels, which reads lower. To estimate one from the other, use the wheel horsepower calculator. To work out power from torque and rpm, use the horsepower calculator.
Both horsepower constants come from exact definitions: the pound, foot and standard gravity for hp, and the kilogram-force and standard gravity for PS. The converter keeps full precision and only rounds what it shows.
Questions
How many hp is 1 kW?
1 kW is 1.341 mechanical hp, or 1.360 metric PS. Divide kW by 0.745699872 to get hp.
How do I convert hp to kW?
Multiply by 0.745699872. 200 hp is 149.14 kW, and 100 hp is 74.57 kW.
How many hp is 150 kW?
150 kW is 201.15 hp, or 203.94 PS in metric horsepower.
What is the difference between hp and PS?
hp is mechanical horsepower (745.7 W) and PS is metric horsepower (735.5 W). 1 PS is 0.9863 hp, so 100 PS is 98.63 hp, and 300 hp is 304.2 PS.