Watt and Ampere Calculator
Electric Motor Tool

Motor Watts to Amps Calculator

Find the full-load current of an AC motor from its power rating. Required for sizing motor branch circuits, breakers, starters, and overload relays per NEC and IEC standards.

Conversion direction
Electrical system
Quick voltage presets
Calculated result1000 W · 120 V · DC
8.333 A
Formula usedI = P / V

Custom voltage is always supported.

Formulas Used

DCI = P / V

No power factor needed for DC circuits.

AC 1φI = P / (V × PF)

Single-phase AC — multiply voltage by power factor.

AC 3φI = P / (√3 × V × PF)

Three-phase AC — divide by √3 ≈ 1.732.

Frequently Asked Questions

How many amps does a 1HP motor draw at 120V single phase?

1 HP = 746 W. At PF 0.85 and efficiency 85%: I = 746 / (120 x 0.85 x 0.85) = 8.59 A. NEC 430 tables list typical single-phase 1HP motor FLA as 16A at 115V — always verify against nameplate.

Why is motor current higher than watts/volts suggests?

Motors have a power factor less than 1 and an efficiency less than 100%. Both factors increase the input current. Always use the nameplate FLA for circuit sizing.