VFD speed calculator

Calculate synchronous motor speed from drive frequency and number of poles, with an optional slip percentage for estimated actual RPM.

What this means

An induction motor's magnetic field turns at synchronous speed. The rotor turns a little slower; that difference is slip. Use the nameplate full load RPM to estimate slip for your motor.

Formula used

  • Synchronous RPM = 120 × frequency ÷ poles
  • Estimated RPM = synchronous RPM × (1 − slip % ÷ 100)
  • Slip % from nameplate = (sync RPM − nameplate RPM) ÷ sync RPM × 100

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