Watts to Amps Calculator
This watts to amps calculator converts between watts, volts, and amps using the power formula. Pick what you want to solve for, enter the two values you know, and you'll get the third instantly. It covers direct current, single-phase AC, and three-phase AC, with a power factor for the AC modes, and it shows the formula it used. It's free, private, and updates as you type.
- Watts to amps and back
- Solve W, V, or A
- DC & AC modes
- Power factor
- Shows the formula
Last updated June 17, 2026 Based on P = V × I Reviewed by the Calcowa team
Enter the two known values above 0.
The highlighted box is the answer. Power factor is used only for the AC modes.
A = W ÷ V = 1500 ÷ 120 = 12.5 A
How do I convert watts to amps?
Watts, volts, and amps are tied together by one rule: power equals voltage times current, or P = V times I. So to get amps you divide the watts by the volts, which means a 1,500-watt load on a 120-volt circuit pulls 12.5 amps. Raise the voltage to 240 and the same power draws half the current, 6.25 amps, since higher voltage moves the same power with less current. For AC you fold in the power factor, and three-phase adds a square root of 3. This watts to amps calculator picks the right form for your current type, so you'll get the answer without juggling the algebra. It's the same rule an electrician uses, and you don't have to remember which version applies, since the tool handles that part.
Converting 1,500 watts, step by step
Here's a 1,500-watt load on a 120-volt DC or resistive circuit. It's the same path the tool runs for any pair of values, and you'll see it match the box above:
- 1
Start with the formulaPower equals volts times amps, so amps equal watts divided by volts.
- 2
Plug in the numbers1,500 watts divided by 120 volts gives the current.
- 3
Read the currentThat works out to 12.5 amps on the circuit.
- 4
Adjust for AC if neededFor single-phase AC you'd divide by the power factor too, and three-phase adds the square root of 3.
Watts to amps at 120V and 240V
Here's the current that common wattages draw on the two household voltages, for DC or a resistive load with a power factor of 1. Notice 240 volts always halves the amps, which is why heavy appliances are wired for it, since they'll pull less current and you won't trip a breaker as easily.
| Watts | Amps at 120V | Amps at 240V |
|---|---|---|
| 500 W | 4.17 A | 2.08 A |
| 1,000 W | 8.33 A | 4.17 A |
| 1,500 W | 12.5 A | 6.25 A |
| 1,800 W | 15 A | 7.5 A |
| 2,400 W | 20 A | 10 A |
Frequently asked questions
Divide the watts by the volts. On a direct current or single-phase circuit the formula is amps equals watts divided by volts, so a 1,500-watt load on a 120-volt circuit draws 12.5 amps. This watts to amps calculator does it for you, and it'll work the other way too, turning amps and volts back into watts whenever you need the reverse. You won't touch a formula.
Power equals voltage times current, written P = V times I. Rearranged, amps are watts over volts, and volts are watts over amps. For single-phase AC you multiply by the power factor, and for three-phase AC you also multiply by the square root of 3. The tool picks the right form once you choose your current type, so you don't have to memorize all three.
On a standard 120-volt circuit, 1,500 watts is 12.5 amps, which is why a 1,500-watt heater nearly maxes out a 15-amp outlet. On a 240-volt circuit the same 1,500 watts is only 6.25 amps, since higher voltage carries the same power at lower current. Enter your own voltage above and you'll see the exact figure, and it's instant.
Power factor describes how well current turns into real power on an AC circuit, from 0 to 1. Simple resistive loads like heaters sit near 1, while motors and some electronics run lower, often 0.8. It only applies to AC, so leave it at 1 for direct current or a purely resistive load. The calculator uses it for the single-phase and three-phase modes, and that's the only time it'll change your answer.
Single-phase power runs on one alternating circuit, which is what homes use. Three-phase uses three offset circuits and is common in industrial gear and large motors, since it delivers power more smoothly. The math differs by that square root of 3 factor, so pick the mode that matches your supply and the amps come out right.
Yes to both. There's no sign-up, no limit, and nothing to install, since it runs in your browser. The values you enter stay on your device and aren't sent anywhere. Bookmark it and you'll have a quick way to size a breaker, check a circuit, or settle a wiring question whenever one comes up.
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