Horsepower from Torque and RPM

Horsepower, kilowatts, and a solve-for selector across HP, torque, and RPM via HP = Torque * RPM / 5252.

Run the calculator

Example

You enter

Solve for hp
Torque (lb-ft) 400
RPM 5000

You get

Horsepower 380.81
Kilowatts 283.96

Details, formula, and sources

HP = Torque(lb-ft) * RPM / 5252 (5252 = 33,000 / 2*pi); kW = HP * 0.7457. Torque and HP are equal at 5252 RPM by definition. Solve for any of {HP, torque, RPM}.

Classical definition of mechanical power (Watt's 33,000 ft-lb/min); SAE J1349 engine-power rating, by name.

The constant 5252 is a pure derivation, fully public.

Estimate. AHJ and licensed professional govern.

Field names used by the API: solve_for, torque_lbft, rpm, hp, kw

Power constant 5252 = 33,000 ft-lb/min per HP / (2*pi rad/rev)definition of horsepower