Mechanical & Drives
Torque from power and speed
Shaft torque from kW or hp and rpm, and power from torque.
Calculating…
How it's calculated
T [Nm] = 9549.3 × P [kW] ÷ n [rpm]
P [kW] = T × n ÷ 9549.3
Imperial: T [lbf·ft] = 5252 × P [hp] ÷ n
Torque and speed trade off through a gearbox: halve the speed and you double the torque, less gearbox losses. Use this for sizing couplings, keys and shafts, or checking a motor against a load.
A 7.5 kW motor at 1460 rpm produces about 49 Nm at full load. Starting torque is typically 1.5–2.5 × this for a standard induction motor.