Motor current calculator

See Also

• Cable sizing calculator AS/NZS3008
• Maximum demand calculator AS/NZS3000
• Wire size calculator NEC

Motor current calculator parameters

• Voltage (V). The phase-to-phase voltage for a 3-phase supply, or the phase-to-neutral voltage for a single phase supply.
• Phase. Whether its a 3-phase or single phase voltage supply.
• Rating (P). The power rating of the motor in kW or hp.
• Power factor (cosΦ). The rated power factor of the motor. Typically around 0.86.
• Efficiency (η). The efficiency of the motor. Typically around 95%. Enter 95.

How do you calculate motor current for a 3 phase and single phase motor?

3-phase motor amps calculation with power rating in kilowatt (kW):

\(I=\displaystyle\frac{1000 \cdot P_{kW}} {\sqrt{3} \cdot V_{LL} \cdot \cos{\phi} \cdot \eta }\)

3-phase motor amps calculation with power rating in horsepower (hp):

\(I=\displaystyle\frac{745.7 \cdot P_{hp}} {\sqrt{3} \cdot V_{LL} \cdot \cos{\phi} \cdot \eta }\)

1-phase motor amps calculation with power rating in kilowatt (kW):

\(I=\displaystyle\frac{1000 \cdot P_{kW}} { V_{LN} \cdot \cos{\phi} \cdot \eta }\)

1-phase motor amps calculation with power rating in horsepower (hp):

\(I=\displaystyle\frac{745.7 \cdot P_{hp}} { V_{LN} \cdot \cos{\phi} \cdot \eta }\)

Note that the motor rated full load current is specified on the motor datasheet and stamped on the motor nameplate. However, this calculator is useful when only the motor rating is available and an estimate of the current is required.