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Watts to Amps Calculator

Convert watts to amps or amps to watts for DC, single-phase and three-phase AC, with power factor. Free watts to amps calculator.

Current
12.5 A
Breaker for a continuous load (125%)
15.6 A or more

Converting watts and amps

Amps = watts ÷ volts for DC and for AC loads with a power factor of 1, like heaters and lights. A 1,500 W space heater on 120 V draws 12.5 A. For motors and other AC loads, divide by the power factor too: amps = watts ÷ (volts × PF). For three-phase power with line-to-line voltage, divide by √3 as well: 10 kW at 400 V and PF 0.85 is 17 A. Size breakers at 125% of a continuous load.

How to use it

  1. 1

    Choose the direction

    Watts to amps, or amps to watts.

  2. 2

    Enter the power or current

    And the voltage.

  3. 3

    Pick the circuit

    DC, single-phase or three-phase AC, with power factor.

Frequently asked questions

How many amps is 1,000 watts?

8.3 A at 120 V, or 4.3 A at 230 V.

How many watts is 15 amps?

1,800 W at 120 V, or 3,450 W at 230 V.

What is power factor?

The share of current that does useful work. It's 1 for resistive loads and about 0.8–0.9 for motors.

Is anything stored?

No. The calculation runs in your browser.

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