Calculates the steady-state shaft torque a motor (or any rotating prime mover, including engines) delivers at its rated (or any operating) power and speed, using the standard power-torque-speed relation. Useful for coupling, gearbox, and mechanical drive-train selection once electrical sizing (see the Motor Calculator) is done.
Standards followed
Standard power-torque-speed relation: T(N·m) = 9550 × P(kW) / N(rpm); T(lb-ft) = 5252 × P(hp) / N(rpm)
What it can do
- Metric (kW → N·m) or imperial (hp → lb-ft) input, with both units shown in the result.
- Works for any operating point, not just nameplate rated speed — useful for VFD speed-range torque checks.
Example problem
37kW motor at 1480 rpm (typical 4-pole 50Hz induction motor slip speed).
- T = 9550 × 37 / 1480 ≈ 238.75 N·m
≈238.75 N·m (≈176.1 lb-ft).
This is steady-state running torque only — starting/breakdown/pull-up torque and acceleration torque during run-up are different quantities (see the Motor Acceleration Time calculator for the acceleration case).