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WattSimple

Watts to Amps Calculator

Convert watts to amps — or amps to watts — for DC, single-phase, and three-phase circuits. Set the voltage and power factor, and WattSimple also shows the NEC breaker and copper wire size the current calls for.

Convert

Current

12.5 A

Power in
1,500 W
At voltage
120 V

NEC wire & breaker for this load

Breaker
15 A
Min. copper wire (75°C)
14 AWG

Copper, 75°C terminations, NEC Table 310.16. Real installs may need derating for ambient heat, conduit fill, or voltage drop. Full wire & breaker chart. Always confirm with a licensed electrician + local AHJ.

Frequently asked questions

For a DC or single-phase circuit, amps = watts ÷ volts (divide by power factor too for AC motors and other reactive loads). For three-phase, amps = watts ÷ (1.732 × line voltage × power factor). Example: 1,500 watts at 120 volts single-phase = 12.5 amps.

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