Horsepower to Amps Calculator

Enter horsepower, voltage, efficiency, and circuit type to instantly calculate the required amperage.

Circuit Parameters

Enter values and click Calculate

Common Motor Voltages

DC: 12, 24, 48, 120, 240 V
1-Phase AC: 115, 120, 208, 230, 240 V
3-Phase AC: 208, 230, 460, 480, 575, 600 V (line-to-line)

Summary

Enter horsepower, voltage, efficiency, and circuit type to instantly calculate the required amperage.

How it works

  1. Select the circuit type: DC, single-phase AC, or three-phase AC.
  2. Enter the motor rating in horsepower (HP).
  3. Enter the supply voltage in volts (V).
  4. Enter the efficiency as a percentage (typically 80–95% for motors).
  5. For AC circuits, enter the power factor (typically 0.8–1.0).
  6. The calculator applies the appropriate formula and displays the current in amps.

Use cases

  • Size circuit breakers and fuses for electric motors.
  • Select the correct wire gauge for motor wiring.
  • Estimate current draw when upgrading or replacing motors.
  • Verify nameplate amperage against rated horsepower and voltage.
  • Design electrical panels for industrial equipment.
  • Compare single-phase vs. three-phase current requirements.
  • Calculate generator or UPS sizing for motor loads.
  • Convert motor specs from imperial (HP) to SI equivalents.

Frequently Asked Questions

Last updated: 2026-06-14 · Reviewed by Nham Vu