3-Phase Current Calculator (kW, kVA to Amps)
How many amps does your load draw?
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3-Phase Current Calculator (kW, kVA to Amps) by TheCalcTools
How the 3-Phase Current Calculator (kW, kVA to Amps) works
Choose three-phase or single-phase and enter the load in kW.
Divide kW by power factor (and efficiency) to get kVA.
Current = kVA × 1,000 ÷ (√3 × line voltage) for three-phase, or ÷ voltage for single-phase.
The formula
Worked example
Using the default values shown in the calculator:
| Supply | Three-phase |
|---|---|
| Load (kW) | 20 |
| Power factor | 0.85 |
| Line voltage (V) | 400 |
| Equipment efficiency (%) | 100 % |
- kVA = 20 ÷ 0.85 = 23.53.
- I = 23,529 ÷ (√3 × 400) = 34.0 A; reactive power 12.39 kVAR.
Result:
| Apparent power (kVA) | 23.53 |
|---|---|
| Line current (A) | 34.0 |
| Reactive power (kVAR) | 12.39 |
Frequently asked questions
Is voltage line-to-line?
For three-phase, yes: 400 V in a 400/230 V system. For single-phase, use the phase-to-neutral voltage (230 V).
Why include power factor?
A low power factor means the same kW needs more current, so cables and breakers must be larger.
Sources and further reading
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This calculator gives estimates for planning only. Electrical installations must be designed, checked and carried out by qualified personnel following local codes and the equipment manufacturer's data. Never rely on this result alone for safety-critical decisions. See our disclaimer.