Horsepower calculator
Calculate horsepower from torque and engine speed, or estimate it from vehicle weight and quarter-mile time.
About this calculator
The first panel uses torque and rpm. The second estimates power from weight and your quarter-mile time, with an optional trap speed.
Results are estimates. Real-world power depends on traction, gearing, weather and the measuring method.
Measurements and terms explained
- Torque
- The twisting force an engine produces, in lb-ft or newton metres.
- rpm
- Revolutions per minute, how fast the engine turns.
- Horsepower (hp)
- A unit of power. 1 hp = 745.7 watts.
- PS
- Metric horsepower, about 0.986 of a mechanical horsepower.
- Trap speed
- The vehicle's speed at the end of the quarter mile.
Common questions
What is the horsepower formula?
Horsepower = torque in lb-ft × rpm ÷ 5,252.
Is horsepower the same as kilowatts?
No. 1 horsepower is about 0.7457 kW, and 1 kW is about 1.341 hp.
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