About the Electrical Power Calculator
Electrical power in watts from voltage, current or resistance, for DC and AC with power factor.
Also known as: watts calculator, power formula electrical, volts times amps, kw calculator, single phase power.
How to use this calculator
- Enter calculate from, power factor (ac) and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
P = V × I × PF = I²R = V²/R
Worked example
Using the values pre-filled in the calculator above:
- Calculate from: Voltage and current
- Voltage = 230 V
- Current = 10 A
- Power factor (AC) = 1
the calculator returns:
- Real power: 2,300 W
- Kilowatts: 2.3
- Apparent power: 2,300 VA
- Energy per hour: 2.3 kWh