Work out coupling torque instantly with clear inputs, formula shown and shareable results.
Nominal torque in newton metres is 9550 times kilowatts divided by rpm. A coupling is then selected on design torque, nominal torque multiplied by a service factor that reflects load character: around 1.2 for smooth centrifugal loads and 2.0 or more for reciprocating machines. Peak capability should be roughly twice the design value to survive start-up.
Nominal torque
T N·m = 9550 x kW / rpm
Design torque
T design = T nominal x service factor
T N·m = 9550 x kW / rpm. Nominal torque in newton metres is 9550 times kilowatts divided by rpm.
Torque pulsation, starting inrush and the possibility of a locked rotor. It is not a safety factor on material strength but an allowance for load duty.
This calculator takes 3 inputs: Transmitted power, Shaft speed, Service factor. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.