Amps to Watts Calculator
Enter current, voltage, phase count, and power factor to calculate watts using the appropriate single or three-phase formula.
Choose the circuit phase and enter measured RMS current, voltage, and power factor. A current value alone cannot determine watts.
Single phase: P = V × I × PF · Three phase: P = √3 × V × I × PF
Real power
A QUICK WALKTHROUGH
How to use this tool
- Enter RMS current and voltage.
- Choose single phase or three phase and enter a power factor greater than 0 and at most 1.
- Calculate and review the real-power result.
Formula and boundary
Single phase uses P = V × I × PF. Three phase uses P = √3 × V × I × PF. Current alone cannot determine watts; voltage, phase, and power factor are required.
Local estimate
This browser-only calculator uses the RMS values you enter. It does not measure a circuit, model harmonics, or provide electrical safety or engineering sign-off.
GOOD TO KNOW
Common questions
Can I calculate watts from amps alone?
No. You also need voltage, phase configuration, and power factor.
Should power factor be 80 or 0.8?
Enter 0.8 for 80%. The field accepts a decimal greater than 0 and at most 1.
Does it support three phase?
Yes. Select three phase to use √3 × V × I × PF.