Horsepower Calculator
Find your engine's horsepower from its torque and rpm, or convert power between horsepower, kilowatts, and metric horsepower (PS). Torque can be in lb-ft or N·m.
Horsepower (hp)
285.6
Check the highlighted fields to see your result.
- Kilowatts (kW)
- 213
- Metric horsepower (PS)
- 289.6
Results are estimates for information only and do not constitute financial, medical, or legal advice.
How it works
Horsepower measures how quickly an engine does work. Torque is the twisting force, and horsepower combines it with how fast the engine is turning. For the conversion mode, the calculator turns the power into watts and then into the other units.
The formulas
hp = torque (lb-ft) × rpm ÷ 5252
1 hp = 0.7457 kW · 1 PS = 0.7355 kW · 1 N·m = 0.7376 lb-ft
Worked example
An engine makes 300 lb-ft of torque at 5,000 rpm.
- hp = 300 × 5,000 ÷ 5,252 = 285.6 hp.
- In kilowatts: 285.6 × 0.7457 = 213.0 kW.
- In metric horsepower: 213.0 ÷ 0.7355 = 289.6 PS.
Frequently asked questions
Why is the number 5252 in the horsepower formula?
Horsepower is defined as 33,000 foot-pounds of work per minute. Working that out for an engine turning at a given rpm gives hp = torque × rpm ÷ (33,000 ÷ 2π), and 33,000 ÷ 2π is about 5,252. It is also why the torque and horsepower curves on a dyno chart always cross at 5,252 rpm.
What's the difference between hp, PS, and CV?
Mechanical horsepower (hp) is 745.7 watts. The metric horsepower, called PS in Germany and CV in many countries, is 735.5 watts, so a PS is about 1.4% smaller. A car listed as 150 PS makes about 148 hp.
Is this crank horsepower or wheel horsepower?
It gives the power for the torque you enter. Engine torque gives crank horsepower, which is what manufacturers advertise. Power measured at the wheels is lower, because the transmission and drivetrain use part of it, typically 10% to 20%.