How Many Amps Is 500 Watts?

Answer
4.2 A at 120 V · 2.1 A at 240 V

Amps = watts ÷ volts. A 500 W resistive load draws 4.2 A at 120 V and 2.1 A at 240 V. On 120 V, a continuous load this size needs a 15 A breaker.

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1.0 for heaters and lights; 0.8–0.9 for motors.
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    For estimating and educational purposes only. Results are approximate and are not a substitute for a licensed professional, the manufacturer's instructions or your local code. Disclaimer

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    Amps, breaker and wire by voltage

    VoltageCurrentBreaker (continuous)Copper wire
    120 V4.2 A15 A14 AWG
    208 V2.4 A15 A14 AWG
    240 V2.1 A15 A14 AWG
    480 V 3-phase0.60 A––

    Breaker sized at 125% for continuous loads (NEC 210.20). Motors and electronics draw more current than watts ÷ volts because of power factor.

    Frequently asked questions

    Can a 15 amp circuit handle 500 watts?

    Yes. A 15 A circuit at 120 V supplies 1,800 W, or 1,440 W for continuous loads, so 500 W fits.

    How many amps is 500 watts at 12 volts?

    42 A at 12 V DC, before inverter losses (about 46 A through a 90% efficient inverter).

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