Watts to Amps Calculator
Watts to amps at any voltage, and back.
The conversion
A = W / V W = V × A
A 2,000 W heater draws 8.7 A at 230 V but 16.7 A at 120 V, which is why high-power appliances are much closer to tripping a 15 A North American breaker than a European 16 A one.
The fine print
These formulas are exact for DC and for resistive AC loads (heaters, kettles, incandescent light). Motors and electronics have a power factor below 1, so they draw more amps than W / V suggests. Breakers are also normally loaded to only 80% continuous, so a '15 A' circuit really means about 1,440 W continuous at 120 V.