How Many Watts Is 20 Amps?

Answer
2,400 W at 120 V · 4,800 W at 240 V

Watts = amps × volts. 20 A at 120 V = 2,400 W and 20 A at 240 V = 4,800 W. A 20 A breaker should carry at most 80% of that for continuous loads: 1,920 W at 120 V.

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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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    20 amps in watts by voltage

    VoltageWattsContinuous (80%)
    12 V240 W192 W
    120 V2,400 W1,920 W
    208 V4,160 W3,328 W
    240 V4,800 W3,840 W
    480 V 3-phase16,628 W13,302 W

    For motors and electronics, multiply by the power factor (typically 0.8–0.95) to get real watts.

    Frequently asked questions

    How many watts can a 20 amp breaker handle?

    2,400 W at 120 V or 4,800 W at 240 V, and 80% of that for continuous loads.

    How many watts is 20 amps at 12 volts?

    240 W.

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