Motor Full-Load Current and Breaker Size Calculator

Enter the motor rating, supply and power factor to get the full-load current, an indicative breaker size and the starting current for DOL and star-delta starters.

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Formulas used

Three phase: I = P / (1.732 x V x pf x efficiency)
Single phase: I = P / (V x pf x efficiency)
1 HP = 0.7457 kW

Frequently asked questions

Should I use this or the nameplate current?

Use the nameplate current when you have it. This calculator gives a good estimate when you only know the kW rating.

Is the breaker size final?

No. It is indicative. Final selection depends on the starter type, short-circuit level and the maker's coordination tables.