Convert kW or kVA to amps and back for single-phase, three-phase and DC circuits.
Supply
Load
The same load on other supplies
Line current, each line
160.4A
Balanced three-phase, 400 V line‑to‑line (230.9 V line‑to‑neutral).
Check the values to see a result.
DC I = P × 1000 ÷ VSingle-phase I = P × 1000 ÷ (V × PF)Balanced three-phase I = P × 1000 ÷ (√3 × VLL × PF)
100 kW at 400 V three-phase with a power factor of 0.9 draws 160.4 A in each line.
Tip: A meter reading in kW is already electrical input. Use a motor’s efficiency only when you start from its nameplate shaft rating.
To convert kW to amps, multiply the power by 1,000 to get watts, then divide by the voltage. On an AC circuit, divide by the power factor as well. For a balanced three-phase load, divide by √3 times the line-to-line voltage. The answer is the current in each line, not a total across the three lines.
I = P × 1000 ÷ V
Batteries, PV strings and 24 V control supplies have no power factor. Current is watts divided by volts: 2 kW at 48 V DC is 41.67 A.
I = P × 1000 ÷ (V × PF)
Use the voltage between the line and neutral, 230 V in Europe and 120 V or 240 V in North America. A power factor below 1 means the circuit carries more current than the real power alone needs.
I = P × 1000 ÷ (√3 × VLL × PF)
This is the usual form: 400 V in Europe, 208 V or 480 V in North America. The √3 comes from the relationship between line-to-line and line-to-neutral voltage in a balanced supply.
I = P × 1000 ÷ (3 × VLN × PF)
If you only have the phase voltage (230 V), multiply it by three instead of √3. Choose “Line-to-neutral” in the calculator and it converts the voltage for you.
I = S × 1000 ÷ (√3 × VLL)
Apparent power already includes the power factor, so it does not appear. Use this for transformer, generator and UPS ratings, which are given in kVA. For single-phase, leave out the √3.
To go the other way, from amps to kW, multiply instead of dividing: P = √3 × VLL × I × PF ÷ 1000 for three-phase and P = V × I × PF ÷ 1000 for single-phase.
A 22 kW AC charger draws close to unity power factor at full output. With PF 0.99: 22 × 1000 ÷ (1.732 × 400 × 0.99) = 32.08 A in each line. That is why 22 kW chargers sit on a 32 A three-phase circuit: 3 × 230 V × 32 A is 22.08 kW.
For several chargers on one supply, the EV charging capacity calculator checks the total against the site limit.
Line current, each line 32.08 A Open in the calculator
A resistive heater has a power factor of 1. Current is 3 × 1000 ÷ 230 = 13.04 A, comfortably within a 16 A circuit.
Line current 13.04 A Open in the calculator
A motor nameplate gives the mechanical output at the shaft, not the electrical input. With 92% efficiency and a power factor of 0.85 from the nameplate, the input is 15 ÷ 0.92 = 16.3 kW and the current is 16.3 × 1000 ÷ (1.732 × 400 × 0.85) = 27.69 A in each line.
Treating the 15 kW as electrical input would give 25.47 A, about 8% low. Choose “Motor shaft output” under More options when you start from a nameplate.
Line current, each line 27.69 A Open in the calculator
Current for common loads at a power factor of 0.9. Three-phase columns give the current in each line. For another power factor, multiply a figure by 0.9 and divide by your power factor, or use the calculator.
| Power (kW) | 230 V single-phase (A) | 208 V three-phase (A) | 400 V three-phase (A) | 480 V three-phase (A) |
|---|---|---|---|---|
| 1 | 4.8 | 3.1 | 1.6 | 1.3 |
| 2 | 9.7 | 6.2 | 3.2 | 2.7 |
| 3 | 14.5 | 9.3 | 4.8 | 4.0 |
| 5 | 24.2 | 15.4 | 8.0 | 6.7 |
| 7.5 | 36.2 | 23.1 | 12.0 | 10.0 |
| 10 | 48.3 | 30.8 | 16.0 | 13.4 |
| 15 | 72.5 | 46.3 | 24.1 | 20.0 |
| 20 | 96.6 | 61.7 | 32.1 | 26.7 |
| 22 | 106.3 | 67.9 | 35.3 | 29.4 |
| 25 | 120.8 | 77.1 | 40.1 | 33.4 |
| 30 | 144.9 | 92.5 | 48.1 | 40.1 |
| 40 | 193.2 | 123.4 | 64.2 | 53.5 |
| 50 | 241.5 | 154.2 | 80.2 | 66.8 |
| 75 | 362.3 | 231.3 | 120.3 | 100.2 |
| 100 | 483.1 | 308.4 | 160.4 | 133.6 |
| 150 | 724.6 | 462.6 | 240.6 | 200.5 |
| 200 | 966.2 | 616.8 | 320.8 | 267.3 |
| 250 | 1,207.7 | 771.0 | 400.9 | 334.1 |
| 300 | 1,449.3 | 925.2 | 481.1 | 400.9 |
| 400 | 1,932.4 | 1,233.7 | 641.5 | 534.6 |
| 500 | 2,415.5 | 1,542.1 | 801.9 | 668.2 |
It depends on the voltage and the power factor. At a power factor of 1, 1 kW is 4.348 A at 230 V single-phase, 8.333 A at 120 V single-phase and 1.443 A in each line at 400 V three-phase.
Per line. Each of the three lines carries the calculated current, and that is the figure you compare with a breaker, a cable rating or a CT. Do not add the three together.
The answer comes out √3 times too high, about 73%, because the formula expects the line-to-line voltage. 100 kW at a power factor of 0.9 is 160.4 A at 400 V but 278.9 A if 230 V is entered as line-to-line. Choose “Line-to-neutral” if 230 V is the figure you have.
Use the measured value or the one on the nameplate. Heaters and incandescent lighting are close to 1. Induction motors run at about 0.8 to 0.9 at full load and lower at part load. Loads with modern power electronics, such as EV chargers and drives with active front ends, are often above 0.95.
If you do not know it, 0.8 gives a higher, more cautious current than 0.9 or 1.
No. It gives the design current. Cable and protection sizing also depend on installation method, grouping, ambient temperature, voltage drop and fault level, which your wiring rules set out. The voltage drop calculator covers one of those checks.
A calculation gives one operating point. A ZEM measures current, voltage and power on all three phases, so you can see the real load over time.
