How to convert amps to watts
For a basic DC circuit, multiply voltage by current. AC calculations can additionally use power factor and a phase multiplier.
Example
A 120-volt DC load drawing 10 amps uses 1,200 watts.
Actual AC systems and equipment can involve additional electrical characteristics. Use equipment specifications and applicable electrical requirements for design work.
Frequently asked questions
How many watts is 10 amps at 120 volts?
For DC or a unity-power-factor load, 1,200 watts.
What is a kilowatt?
One kilowatt equals 1,000 watts.
Why does AC use power factor?
In AC circuits, current and voltage may not contribute to real power in the same way as a simple resistive DC load.
Using this calculator effectively
The amps-to-watts calculator converts electrical current and voltage into real power for DC, single-phase AC or three-phase AC. For AC calculations, power factor is included because current alone does not always translate directly into real power.
Common uses
- Estimating watts from a known current draw and voltage.
- Comparing DC and AC power calculations.
- Converting a result into kilowatts for easier comparison with larger loads.
Tips for a better estimate
- Use the correct line voltage and phase configuration for the system.
- Enter a realistic power factor for AC loads instead of assuming 1 unless appropriate.
- Use equipment nameplate or measured data for design decisions rather than rough estimates alone.
Related calculations
Watts to Amps Calculator · Ohm's Law Calculator · Voltage Drop Calculator