Amps to kW – 3 Phase Calculator
Convert three phase line current to real power in kW and apparent power in kVA. Enter line current, line voltage, and power factor for any three phase system.
This calculator provides estimates only. Always consult a qualified electrician for real installations.
Three Phase Amps to kW
Result
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Real Power (Watts)
—
Real Power (kW)
Formula
kW = (√3 × Vline × I × PF) ÷ 1000
kVA = (√3 × Vline × I) ÷ 1000
kVA = (√3 × Vline × I) ÷ 1000
kW per amp at common voltages (PF = 0.85):
| Voltage | kW per amp (PF 0.85) | kW per amp (PF 0.9) |
|---|---|---|
| 400V three phase | 0.589 kW/A | 0.624 kW/A |
| 415V three phase | 0.611 kW/A | 0.647 kW/A |
| 480V three phase | 0.707 kW/A | 0.748 kW/A |
Frequently Asked Questions
How do I convert amps to kW in three phase?
kW = (√3 × V × I × PF) ÷ 1000. For 415V, 36A, PF=0.85: kW = (1.732 × 415 × 36 × 0.85) ÷ 1000 = (1.732 × 415 × 30.6) ÷ 1000 = 21,994 ÷ 1000 = 22 kW. This is the real power drawn by the load.
How do I find power factor when converting amps to kW?
If you have both a wattmeter reading (kW) and an ammeter reading with known voltage (kVA), PF = kW ÷ kVA. For unknown loads, use 0.85 as a conservative estimate for industrial loads. Check motor nameplates — they usually list rated PF. For pure resistive loads (heaters), PF = 1.0.
What is the difference between kW and kVA for three phase?
kVA = √3 × V × I ÷ 1000 (apparent power — what the system must deliver). kW = kVA × PF (real power — useful work). A motor drawing 50A on 415V three phase: kVA = 1.732 × 415 × 50 ÷ 1000 = 35.9 kVA. At PF=0.85: kW = 35.9 × 0.85 = 30.5 kW. The difference (35.9 − 30.5 = 5.4 kVAR) is reactive power.