Watts to amps and amps to watts
Convert power to current (or back) to size outlets, wires, fuses or power supplies.
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How it is calculated
DC: I = P / V
Single-phase: I = P / (V · PF)
Three-phase: I = P / (√3 · V · PF)
For three-phase, V is the line-to-line voltage (208 or 480 V in the US, 400 V in Europe). The power factor is 1 for resistive loads such as heaters and lower for motors, LEDs and electronics.
Frequently asked questions
How many amps is 1000 watts?
8.33 A at 120 V, 4.17 A at 240 V and 83.3 A at 12 V DC.
How many watts can a 15 amp outlet handle?
1800 W at 120 V. For continuous loads the NEC limits it to 80 %, about 1440 W.
Why divide by √3 for three-phase?
Because the power is shared by three phases 120° apart, and line voltage is √3 times the phase voltage.