Amps to Watts Calculator
Convert amps to watts with this calculator. Enter current in amps and the voltage to find power in watts, using the formula watts equals amps times volts.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Amps to Watts Calculator Works
This calculator converts current in amps into power in watts using the supply voltage. Amps measure how much current flows, while watts measure how much power is delivered. They are connected by voltage through the power equation W = A × V.
The Formula
Watts = amps × volts
Power is current multiplied by voltage. To find power, multiply the current by the voltage of the supply.
Worked Example
A device drawing 12.5 A on a 120 V circuit:
- Watts = 12.5 × 120 = 1,500 W
The same current on a 240 V supply:
- Watts = 12.5 × 240 = 3,000 W
Doubling the voltage doubles the power for the same current, which is why higher-voltage systems can deliver more power through the same wiring.
Amps to Watts Quick Reference (at 120 V)
| Amps | Watts (120 V) |
|---|---|
| 5 | 600 |
| 10 | 1,200 |
| 15 | 1,800 |
| 20 | 2,400 |
| 30 | 3,600 |
AC, DC and Power Factor
For DC circuits and resistive AC loads (heaters, kettles, incandescent bulbs) the formula above is exact. For reactive AC loads such as motors, multiply by the power factor (often 0.8 to 0.95), so watts = amps × volts × power factor.
Frequently asked questions
How do I convert amps to watts?+
Multiply the current in amps by the voltage. For example, 12.5 amps at 120 volts is 12.5 × 120 = 1,500 watts. You need the voltage because amps alone do not determine power.
How many watts is 10 amps?+
It depends on voltage. At 120 V, 10 amps is 1,200 watts. At 240 V, 10 amps is 2,400 watts. The same current produces more power at higher voltage.
Why do I need the voltage to convert amps to watts?+
Power equals current times voltage (W = A × V). Without the voltage you cannot calculate power from current alone, so the converter always asks for the supply voltage.
Does this work for AC and DC?+
It works directly for DC and for resistive AC loads with a power factor of 1, such as heaters and incandescent bulbs. For motors and reactive loads, multiply the result by the power factor too.
What voltage should I enter?+
Use your supply voltage: typically 120 V in North America, 230 V in Europe and the UK, or 12 V and 24 V for vehicle and battery systems. The device or breaker label usually states it.