Horsepower to Amperes Calculator for AC Motors

This calculator is to find amps of AC motors. You can find amperes for both single phase and three phase motors when HP of motor is known to you.

How to use the calculator?

• From the drop down, select the phase.
• For this calculator, note down the voltage, efficiency, power factor and HP of the motor. You can find details from the motor nameplate.
• Enter the data collected in respective fields.
• You can take value 0.8 for pf and 0.8 for efficiency if it is not available on motor name plate.
• The calculator would show automatically the calculated value.

How to calculate amperes when horse power is known?

Formula for Calculating amperes for single phase AC Motor

For single phase, amperes (I) is equal to horse power (HP) multiply by 746 whole divided by Voltage (V) multiply by Power Factor (PF) multiply by Efficiency (EFF).

Example

Let us say you have 100 HP motor with rated voltage 230 VAC, power factor 0.85 and efficiency 0.93, then the input current of motor is 410.307 amps.

Formula for calculating amperes for three phase AC Motor

For three phase, amperes (I) is equal to horse power (HP) multiply by 746 whole divided by Voltage (V) multiply by Power Factor (PF) multiply by Efficiency (EFF) multiply by square root of 3.

Example

Let us say we have 100 HP motor with rated voltage as 415 VAC, power factor as 0.85 and efficiency as 0.93, then the input current of motor is 131.445 amps.