🔌 HP to Amps Calculator
Convert motor horsepower to amps for DC, single-phase, or three-phase circuits.
Converting Horsepower to Amps
To find the current drawn by an electric motor, its mechanical horsepower output is first converted to electrical watts (1 hp = 746 W), then divided by the applicable voltage relationship, accounting for motor efficiency and, for AC circuits, power factor. For DC: I = (hp×746)/(V×η). For single-phase AC: I = (hp×746)/(V×η×PF). For three-phase AC: I = (hp×746)/(V×η×PF×√3).
Efficiency (η) accounts for internal motor losses (the electrical input power always exceeds the mechanical output), while power factor (PF) accounts for the phase difference between voltage and current in AC circuits. The √3 factor in the three-phase formula reflects how power splits across three conductors instead of two. This is a standard electrical-engineering reference calculation for sizing wiring and breakers — always consult the motor’s nameplate and local electrical code for actual installations.