Watts to Amps Calculator
Convert between watts, amps and volts for DC or AC power. Pick what to solve for, choose the current type, and add a power factor for AC single-phase or three-phase loads.
This free watts to amps calculator converts between watts, amps and volts for any supply. Pick the quantity to solve for, choose DC, AC single-phase or three-phase, and it recalculates live as you type. As a volts, amps, watts converter it handles the power factor that AC motors and electronics draw, so the current comes out right rather than assuming a perfect load. Everything runs in your browser, nothing uploaded.
Convert
Current
10 A
DC
- Power (W)
- 1,200 W
- Current (A)
- 10 A
- Voltage (V)
- 120 V
- Power factor
- 1.0 (DC)
Formula: P = V × I. The value you solve for is highlighted; the two you type stay put when you switch the target.
A planning estimate. Real loads shift with inrush current, harmonics and the true power factor of your equipment, so size wire, breakers and fuses to code with a safety margin.
How it works
- 1
Choose what to solve for
Pick amps, watts or volts. The two inputs you need appear; the third is worked out.
- 2
Set the current type
DC for batteries and solar, or AC single-phase or three-phase for mains. A power factor field appears for AC.
- 3
Read the conversion
See the solved value and the full watts, amps and volts set, ready to size wire and breakers.
Instant & 100% private — nothing is uploaded
Every calculation runs locally in your browser. The income, balances and goals you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.
Frequently asked questions
- How do I convert watts to amps?
- Divide the watts by the volts. On DC or a resistive AC load at 120 V, 1200 W draws 1200 / 120 = 10 amps. For an AC motor you also divide by the power factor, so at 0.9 the same load pulls about 11.1 amps.
- What is power factor and when do I use it?
- Power factor is how much of the AC supply does real work, from 0 to 1. Resistive loads like heaters sit near 1.0; motors and switch-mode electronics run around 0.8 to 0.9. It only applies to AC, so the field is hidden on DC.
- How is three-phase different?
- Three-phase power adds a √3 (about 1.732) factor and uses the line-to-line voltage. Watts equal √3 × volts × amps × power factor, which is why a three-phase feeder carries less current than a single-phase one for the same power.
- How is this different from an Ohm's law calculator?
- An electrical power converter here works in watts, amps and volts with a current type and power factor, which is what you read off a nameplate or breaker. Ohm's law adds resistance and assumes an ideal DC circuit, so use that when you know the resistance instead.
- Can I convert amps to watts?
- Yes. Set it to solve for watts, enter the volts and amps, and pick the current type. On AC it multiplies by the power factor, and on three-phase by √3 as well, to give the real power in watts.
- How accurate is the result?
- The arithmetic is exact for the numbers you enter, but a real load is not. Inrush current at start-up, harmonics and a power factor that drifts with load all move the true amperage, so size wire, breakers and fuses to code with a margin rather than to the exact figure.
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