Watts to amps calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- I = P ÷ V = 1,500 ÷ 120 = 12.5.
- Size wires and breakers by the electrical code that applies where you live, not by this figure alone.
| Inputs | Answer |
|---|---|
| Power: 1500; Voltage: 120; Circuit: DC (or AC at power factor 1, single phase); Power factor: 0.9 | 1,500 W at 120 V draws 12.5 amps. |
| Power: 3000; Voltage: 230; Circuit: AC single phase with a power factor; Power factor: 0.9 | 3,000 W at 230 V draws 14.493 amps. |
| Power: 10000; Voltage: 400; Circuit: AC three phase (line voltage) with a power factor; Power factor: 0.85 | 10,000 W at 400 V draws 16.981 amps. |
How to use it
For DC, current = watts ÷ volts: 1,500 W at 120 V is 12.5 A. For single-phase AC divide by volts × power factor, and for three-phase AC by √3 × line voltage × power factor. The power factor of a resistive load is 1; motors and other loads are lower.
Wire and breaker sizing are set by the electrical code where you live; use this figure as one input, not the whole answer.
Frequently asked questions
How do I convert watts to amps?
Divide watts by volts (DC), adjusting for power factor in AC.
How many amps is 1,500 watts at 120 volts?
12.5 amps.
What is power factor?
The ratio of real power to apparent power in an AC circuit, between 0 and 1.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
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General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.