Torque, power and RPM calculator

Power = torque × angular speed. Enter any two and get the third in the units you use.

Formulas

P (kW) = T (N·m) × rpm / 9,549.3
P (hp) = T (lbf·ft) × rpm / 5,252
T (N·m) = 9,549.3 × P (kW) / rpm

The constants come from P = T × ω with ω = 2π × rpm / 60. The 5,252 constant is 33,000 / 2π, where 33,000 ft·lbf/min is one horsepower. This is why torque and horsepower curves cross at 5,252 rpm.

Worked example

A motor delivers 200 N·m at 3,000 rpm: P = 200 × 3,000 / 9,549.3 = 62.83 kW, which is 84.3 hp.

Shaft power only. It ignores gearbox and drive losses; apply efficiency separately.

Torque converter · Power converter