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Horsepower Calculator
Enter torque and engine RPM to get horsepower and kilowatts.
Horsepower
—
From torque & RPM.
| Kilowatts | — |
|---|---|
| Torque | — |
| RPM | — |
| — |
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Enter your figures above to see the step-by-step working.
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How the Horsepower Calculator Works
Horsepower and torque are linked by engine speed: one horsepower is defined as 33,000 lb-ft of work per minute, which works out to torque times RPM divided by 5,252. That constant is why every engine’s horsepower and torque curves cross at 5,252 RPM.
Enter the torque in pound-feet and the engine speed in RPM to get the horsepower at that point, plus the metric equivalent in kilowatts (1 hp = 0.7457 kW).
horsepower = torque (lb-ft) × RPM ÷ 5252
Frequently Asked Questions
How do you calculate horsepower from torque?
Multiply torque (lb-ft) by engine speed (RPM) and divide by 5,252. At 350 lb-ft and 5,000 RPM that’s about 333 hp.
Why 5252?
It comes from the definition of one horsepower (33,000 lb-ft/min) divided by 2π radians per revolution. It’s also the RPM where hp and torque curves always cross.
How many kilowatts is one horsepower?
One mechanical horsepower equals about 0.7457 kilowatts.
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