Full-load torque from power and speed in SI and US units, and why a 50 hp motor at 60 Hz produces less torque than a 37 kW motor at 50 Hz.
| Motor A (IEC, 50 Hz) | 37 kW, 4-pole, 1,480 rpm rated speed |
| Motor B (NEMA, 60 Hz) | 50 hp, 4-pole, 1,780 rpm rated speed |
| Check | Requirement | Actual | Status |
|---|---|---|---|
| Motor A full-load torque | n/a | 238.8 N·m | ✓ PASS |
| Motor B full-load torque | n/a | 200.0 N·m | ✓ PASS |
Key insight: Torque, not power, decides whether a motor can drive a load at a given speed. When a 60 Hz motor is replaced by a 50 Hz one of the same kW (or the reverse), check the torque and the driven machine's speed, not just the power rating.
Every input in this example is editable in the live calculator — no signup needed.
Open Motor Torque Calculator calculator →Use the rated (nameplate) speed for full-load torque. Synchronous speed (1,500 or 1,800 rpm for 4 poles) gives a slightly lower, non-physical value because the motor never reaches it under load.