About the Volts to kW Calculator
To get kilowatts from volts you also need the current. This calculator multiplies volts by amps, adds the power factor for AC and √3 for three-phase, then divides by 1,000 to give kilowatts. Use it to check how much power a circuit can deliver, to estimate the load of a machine from its plate, or to compare a 230 V single-phase supply with a 400 V three-phase one. Type the numbers and the kW and watts update as you go, all inside your browser.
Updated October 2026
How to use the Volts to kW Calculator
- 1Choose the type of supply.
- 2Enter the voltage. For three-phase, use the line-to-line voltage.
- 3Enter the current in amps.
- 4For AC, enter the power factor.
- 5Read the power in kW and watts.
What the result tells you
The kilowatt figure is the real power the circuit delivers at that voltage and current. Compare it with a breaker rating to see how much load a circuit can carry, or multiply it by hours of use to estimate energy in kWh. For a running cost estimate, our kW to kWh and energy cost calculators take it from there.
Formulas for each supply
The calculator uses the line-to-line voltage for three-phase supplies because that is the voltage normally quoted, such as 400 V or 480 V.
- DC: kW = V × A ÷ 1,000
- Single-phase AC: kW = V × A × PF ÷ 1,000
- Three-phase AC: kW = √3 × V × A × PF ÷ 1,000
Common examples
A 120 V, 15 A household circuit in the US gives up to 1.8 kW. A 230 V, 13 A UK plug gives up to about 3 kW. A 240 V, 40 A cooker circuit gives 9.6 kW. A 480 V three-phase motor drawing 50 A at a power factor of 0.85 uses about 35.3 kW.
Why three-phase delivers more power
A three-phase supply carries three currents that peak at different moments, so the same cable size can deliver about 1.73 times the power of a single phase at the same line voltage. That is why workshops, farms and fast chargers use it. If you are deciding between a single-phase and a three-phase connection, enter the same current in both modes and compare the kilowatts.
On any device
The page is light and works on old phones as well as computers. The answer appears while you type, and the copy button saves you retyping it into a message or a spreadsheet. Power from voltage needs the current too. Reverse the sum with the kW to Volts Calculator, find the watts with the Volts to Watts Calculator, and see energy used with the kW to kWh Calculator.
Features
- Volts and amps to kW
- Watts shown alongside
- DC, single-phase and three-phase AC
- Power factor for real power
- One-tap copy
- No sign-up and nothing uploaded
Frequently asked questions
How do I convert volts to kW?
Multiply volts by amps and divide by 1,000. For single-phase AC also multiply by the power factor; for three-phase multiply by √3 and the power factor. 230 V × 16 A × 1 ÷ 1,000 = 3.68 kW.
How many kW is a 32 A three-phase supply at 400 V?
√3 × 400 × 32 ÷ 1,000 ≈ 22.2 kW at a power factor of 1, which is why 22 kW is the common three-phase EV charger size.
Can I find kW from volts alone?
No. Voltage is only the pressure; the power also depends on how much current flows. Enter the current from a clamp meter, the rating plate or the breaker size.
What is the difference between kW and kVA?
kW is real power, the part that does work. kVA is apparent power, volts times amps without the power factor. They are equal only when the power factor is 1.
What power factor should I use?
1 for heaters and resistive loads, about 0.95 for modern electronics with power factor correction, and 0.8 to 0.9 for motors.
Does it work for DC solar and battery systems?
Yes. Choose DC; a 48 V battery bank delivering 100 A supplies 4.8 kW.