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Amps to kW Calculator

Choose the direction, the system type and the voltage, then enter the amps or the kilowatts. You get the other value, the power in watts, the apparent power in kVA and the power factor used.

Your numbers

Result

How we calculate it

Power in watts is voltage times current times power factor. For DC the power factor is 1. For three phase AC there is an extra factor of 1.732 (the square root of 3): watts = 1.732 × volts × amps × power factor.

Kilowatts are watts divided by 1000. For example 30 A at 240 V single phase with a power factor of 0.9 is 240 × 30 × 0.9 = 6,480 W = 6.48 kW. Going the other way, amps = watts ÷ (volts × power factor), with the 1.732 factor for three phase.

Apparent power in kVA ignores the power factor: volts × amps (× 1.732 for three phase) ÷ 1000. A resistive load such as a heater has a power factor of 1, so kW and kVA are equal; motors are often 0.8 to 0.9.

Assumptions and limits

  • This is a planning estimate, not electrical advice. Wiring must follow the electrical code adopted where you live, and a licensed electrician or permit inspector decides what is safe for your job.
  • Use the power factor on the nameplate. If you do not know it, 0.9 is a reasonable guess for mixed AC loads and 1 for heaters and incandescent lights.
  • Voltage is line to line for three phase systems (for example 208 V or 480 V).

Frequently asked questions

How many kW is 30 amps at 240V?

With a power factor of 1, 30 A × 240 V = 7.2 kW. With 0.9, it is 6.48 kW.

How do I convert amps to kW for three phase?

Multiply 1.732 by the line voltage, the amps and the power factor, then divide by 1000. For 50 A at 208 V and 0.9: 1.732 × 208 × 50 × 0.9 = 16.2 kW.

How many amps is 10 kW at 240V?

About 41.7 A at a power factor of 1 (10,000 ÷ 240), and 46.3 A at a power factor of 0.9.

What is the difference between kW and kVA?

kW is real power that does work. kVA is apparent power, the total the wiring and generator must supply. They differ by the power factor.

Do I need the power factor for DC?

No. For DC the power factor is 1, so watts are simply volts times amps.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Convert = Amps to kW; System = Single phase AC; Voltage (V) = 240; Current (amps) = 30; Power factor (0.1 to 1) = 0.9.

  • Power 6.480 kW
  • Current 30.00 A
  • Power in watts 6,480 W
  • Apparent power 7.200 kVA
  • Power factor used 0.90

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.