Amps to watts calculator
Enter the amps and the voltage. You get the watts, kilowatts and VA for DC, single-phase or three-phase power, with the power factor of the load.
Inputs
Result
Amps to watts chart
Watts for common currents, power factor 1.
| Amps | 12 V DC | 120 V | 240 V |
|---|
How to convert amps to watts
A 15 A circuit at 120 V carries up to 15 x 120 = 1,800 W. A 30 A dryer circuit at 240 V carries 7,200 W. A 20 A three-phase load at 208 V with a power factor of 0.9 is 1.732 x 20 x 208 x 0.9 = 6,485 W.
Watts and VA
Volts times amps gives volt-amperes (VA), the apparent power. For heaters and lights they are the same as watts. For motors and electronics the watts are lower, by the power factor. Generators, UPS units and transformers are rated in VA or kVA because the current, not just the real power, is what heats their windings.
Going the other way? Use the watts to amps calculator. For a generator, the generator sizing calculator adds up running and starting watts.
Questions
How many watts is 1 amp?
120 watts at 120 V, 240 watts at 240 V and 12 watts at 12 V. Watts = amps x volts.
How many watts is 30 amps?
3,600 W at 120 V and 7,200 W at 240 V. For a continuous load, 80% of that: 5,760 W at 240 V.
How many watts is 13 amps?
1,560 W at 120 V, 3,120 W at 240 V, and 2,990 W at the 230 V used in the UK, where 13 A is the plug fuse rating.
How many watts is 20 amps?
2,400 W at 120 V and 4,800 W at 240 V; 1,920 W and 3,840 W for a continuous load.
How do I convert amps to kilowatts?
Multiply amps by volts and divide by 1,000. For three-phase, multiply by 1.732 as well, and for AC by the power factor. 50 A at 240 V is 12 kW.
How many watts is 100 amps?
24,000 W, or 24 kW, at 240 V single-phase. A 100 A service can't run that continuously; the NEC load calculation decides what it can carry.
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