How to use this amps to watts calculator
- Current, enter the current in amps (A).
- Voltage, enter the voltage in volts (V), for example 120 or 240.
- Current type, choose DC, AC single-phase or AC three-phase.
- Power factor, set the power factor for AC loads (DC ignores it). Read the result in watts and kilowatts, updated instantly as you type.
Nothing is submitted or stored: the numbers never leave your device, so you can check appliance and circuit figures privately.
Amps to watts formula
Power is current multiplied by voltage. The exact formula depends on whether the circuit is direct current (DC) or alternating current (AC), and on the power factor for AC loads:
- DC: W = A x V
- AC single-phase: W = A x V x PF
- AC three-phase: W = √3 x A x V x PF (about 1.732 x A x V x PF, using line-to-line voltage)
To get kilowatts, divide the result by 1000. For example, a DC load drawing 5 A at 120 V is600 W, or 0.6 kW. The same current and voltage on an AC single-phase circuit with a power factor of 0.8 gives 480 W.
A note about power factor
Power factor (PF) only matters for AC circuits. It is a number between 0 and 1 that describes how effectively the current is being converted into useful work. Purely resistive loads such as heaters, incandescent bulbs and kettles sit very close to 1.0. Inductive loads like motors, transformers and many electronics run lower, often between 0.7 and 0.9. When you do not know the exact figure, 0.8 is a reasonable default. DC circuits have no power factor, so it is ignored when you select DC.
Frequently asked questions
How do you convert amps to watts?
Multiply the current in amps by the voltage. For DC, watts = amps x volts, so 5 A at 120 V is 600 W. AC circuits also multiply by the power factor.
What is the formula for AC single-phase?
For AC single-phase, watts = amps x volts x power factor. The power factor accounts for the phase difference between current and voltage.
How do I convert amps to watts for three-phase power?
For AC three-phase, watts = √3 x amps x volts x power factor, which is about 1.732 x amps x volts x PF when using line-to-line voltage.
What power factor should I use?
Resistive loads are near 1.0, while motors and electronics often run 0.7 to 0.9. If you are unsure, 0.8 is a common default.
Is my data uploaded?
No, everything is calculated on your device and nothing is sent anywhere.