Motor RPM Calculator
Calculate synchronous and actual RPM for electric motors
Motor RPM Calculator
Compliant with NEMA and IEC Standards
Results:
Synchronous RPM: 0.00
Actual RPM: 0.00
How to Use the Calculator
Input Frequency
- Enter the electrical supply frequency in Hertz (Hz).
- Common values are 50 Hz or 60 Hz.
Input Number of Poles
- Enter the number of poles of the motor.
- Poles always come in pairs (e.g., 2, 4, 6, 8).
Input Slip (Optional)
- Enter the motor's slip as a percentage (%).
- If unknown, leave as 0 for synchronous RPM.
Motor RPM Fundamentals
Synchronous Speed
The synchronous speed is the speed of the rotating magnetic field in the stator.
- Determined by frequency and number of poles.
- Ideal speed without any load or losses.
Actual Speed (Rotor Speed)
- The actual rotational speed of the motor's rotor.
- Always slightly less than synchronous speed due to slip.
- Slip is necessary for torque production in induction motors.
Key Formulas:
Synchronous RPM = (120 × Frequency) / Number of Poles
Actual RPM = Synchronous RPM × (1 - Slip / 100)
Calculation Formulas
Synchronous RPM:
N_s = (120 × f) / P
Actual RPM:
N_r = N_s × (1 - s / 100)
Example Calculation
Motor with 60 Hz Frequency, 4 Poles, and 3% Slip:
Frequency (f): 60 Hz
Poles (P): 4
Slip (s): 3%
Synchronous RPM (N_s) = (120 × 60) / 4 = 1800 RPM
Actual RPM (N_r) = 1800 × (1 - 3 / 100) = 1800 × 0.97 = 1746 RPM
Synchronous RPM = 1800.00 | Actual RPM = 1746.00
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