Horsepower Calculator

Horsepower is torque multiplied by engine speed, and this page works that relation in either direction. Enter torque and RPM to get power in horsepower, kilowatts and metric PS, or enter horsepower and RPM to get the torque behind it. A third tab converts a chassis dyno reading at the wheels into a flywheel figure at whatever drivetrain loss you choose. The constant 5252 is 33,000 foot-pounds per minute divided by two pi, and the working is shown rather than hidden.

Calculator Type
Torque Unit
The torque the engine makes at the engine speed below, not its peak torque at some other speed.
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The speed at which that power figure was measured.
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A rule of thumb, not a measurement: roughly 10 to 15 per cent for a manual, 15 to 20 for an automatic, and 20 to 25 for all-wheel drive. Use a figure someone has actually measured on your car if you have one.
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Related Tools
Engine Displacement Calculator Quarter Mile Calculator RPM Calculator 0-60 Calculator