Induction Motor Calculator

Calculate the synchronous speed, slip and rated torque for an induction motor

Tip: registered users can save calculations.


  • f  -  system frequency (Hz)
  • nr  - rated (or rotor) speed (rpm)
  • ns  - synchronous speed (rpm)
  • P   - number of poles
  • Pr  - motor rated power (kW)
  • S   - motor slip (%)
  • Tr  - rated torque (Nm)


Synchronous Speed

n s = 120f P

Rotor Slip

S= n s n r n s ×100%

Note: for locked rotor nr = 0, therefore S = 1. The slip will decrease as the rotor speed increases.

Rated Torque

T r = 9550 P r n r

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