kW to amps calculator
Enter real power in kilowatts, the system voltage and power factor. Three-phase uses line-to-line voltage.
Quick reference
| kW | 240 V 1-ph | 208 V 3-ph | 480 V 3-ph |
|---|---|---|---|
| 1 kW | 4.17 | 2.78 | 1.2 |
| 3 kW | 12.5 | 8.33 | 3.61 |
| 5 kW | 20.83 | 13.88 | 6.01 |
| 7.5 kW | 31.25 | 20.82 | 9.02 |
| 10 kW | 41.67 | 27.76 | 12.03 |
| 15 kW | 62.5 | 41.64 | 18.04 |
| 20 kW | 83.33 | 55.51 | 24.06 |
| 25 kW | 104.2 | 69.39 | 30.07 |
| 50 kW | 208.3 | 138.8 | 60.14 |
| 75 kW | 312.5 | 208.2 | 90.21 |
| 100 kW | 416.7 | 277.6 | 120.3 |
Amps at power factor 1. Divide by your PF (e.g. ÷ 0.9) for motor loads.
The formulas
DC: P = V × I, so I = P ÷ V
AC single-phase: P = V × I × PF, so I = P ÷ (V × PF)
AC three-phase: P = 1.732 × VLL × I × PF, so I = P ÷ (1.732 × VLL × PF)
PF is power factor, between 0 and 1. Resistive loads (heaters, incandescent lamps, water heaters) are 1. Motors, compressors and power supplies are lower, which means they draw more current for the same watts.
Using the result safely
- Nameplate current beats a calculation. If the equipment lists amps, use that figure.
- For a load that runs 3 hours or more (EV charger, water heater, space heater), the NEC sizes conductors and breakers at 125% of the load.
- To pick the conductor for the current you found, go to the wire size calculator; for long runs check the voltage drop.
Questions people ask
How many amps is 10 kW?
41.7 A at 240 V single-phase (PF 1). On 480 V three-phase at PF 0.9 it is 10,000 ÷ (1.732 × 480 × 0.9) = 13.4 A.
What is the kW to amps formula for three-phase?
I = (kW × 1000) ÷ (√3 × V × PF), where V is line-to-line voltage.
Can I convert kWh to amps?
Only if you know the time. Divide kWh by hours to get average kW, then convert kW to amps. 12 kWh over 4 hours is 3 kW, or 12.5 A at 240 V.