Power converter – kW, PS, hp and bhp

Engine power is given in kilowatts, metric horsepower (PS) or mechanical horsepower (hp/bhp). Convert between the units and calculate power from torque.

Kilowatt (kW)	kW
Metric horsepower (PS)	PS
Mechanical horsepower (hp / bhp)	hp
Approximate rear wheel power (whp)	hp

Kilowatt (kW)	kW
Metric horsepower (PS)	PS
Mechanical horsepower (hp / bhp)	hp
Torque in pound-feet	lb-ft

Results are calculated estimates. Always check your vehicle manufacturer's instructions.

What is the difference between kW, PS, hp and bhp?

kW (kilowatt)

The official SI unit. In the EU the power on the vehicle registration document is given in kilowatts. 1 kW = 1000 W.

PS (metric horsepower)

The most common horsepower in Europe (German Pferdestärke, also CV or ch). 1 PS = 735.5 W.

hp (mechanical horsepower)

British and US horsepower: 1 hp = 745.7 W, about 1.4% more than metric. So the same engine has a slightly smaller number in hp than in PS.

bhp (brake horsepower)

Engine power at the crankshaft, without drivetrain losses. The unit is the same as hp – "brake" refers to where it is measured, not a different unit. Manufacturers usually quote crankshaft power.

whp (wheel horsepower)

Power measured at the rear wheel on a dyno. The drivetrain (gearbox, chain, tyre) usually loses 8–15% of the power, so whp is lower than the manufacturer's figure.

	kW	PS	hp
1 kW	1	1.360	1.341
1 PS (PS)	0.7355	1	0.9863
1 hp (bhp)	0.7457	1.0139	1

How is power calculated from torque?

Power (kW) = torque (Nm) × rpm ÷ 9549. That is why peak power is always at higher rpm than peak torque.

How to use

Enter the power and choose the unit – the calculator shows the same power in the other units.
To calculate power from torque, enter the torque (Nm) and the rpm at which it is reached.
The registration document gives the power in kilowatts (kW).

Frequently asked questions

Are 100 PS and 100 hp the same?

Almost, but not quite: 100 hp = 101.4 PS = 74.6 kW. The difference is about 1.4%.

Why is the dyno result lower than the manufacturer's figure?

Manufacturers usually quote crankshaft power (bhp), while a dyno measures at the rear wheel (whp). The difference comes from drivetrain losses and is typically 8–15%.

What is the A2 licence power limit?

An A2 category motorcycle may have up to 35 kW (about 47.6 PS) and a power-to-weight ratio of up to 0.2 kW/kg.

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