kW to Amps Calculator
Convert between kilowatts and amps for single-phase and three-phase systems. Includes power factor adjustment, voltage presets, and step-by-step formula breakdown.
How to Convert kW to Amps
The electrical formulas used for both single-phase and three-phase conversions.
kW to Amps Formulas
Where I = current in amps, P = power in kilowatts, V = voltage, PF = power factor, and Eff = efficiency (as decimal). For motors, efficiency accounts for energy lost as heat, so more current is drawn for the same output power.
Amps to kW Formulas
Apparent and Reactive Power
Apparent power (kVA) represents total power drawn from the source. Reactive power (kVAR) is the power that oscillates between source and load (inductive/capacitive). Power factor is the ratio of real power (kW) to apparent power (kVA): PF = kW / kVA.
NEC Wire Ampacity Reference
Recommended copper wire gauge based on ampacity at 60°C per NEC Table 310.15(B)(16).
| AWG | Ampacity (60°C) | Max kW @ 240V 1Φ | Max kW @ 208V 3Φ |
|---|---|---|---|
| 14 | 25 A | 6.0 kW | 7.2 kW |
| 12 | 30 A | 7.2 kW | 8.6 kW |
| 10 | 40 A | 9.6 kW | 11.5 kW |
| 8 | 55 A | 13.2 kW | 15.8 kW |
| 6 | 75 A | 18.0 kW | 21.6 kW |
| 4 | 95 A | 22.8 kW | 27.3 kW |
| 2 | 130 A | 31.2 kW | 37.4 kW |
| 1 | 150 A | 36.0 kW | 43.2 kW |
| 1/0 | 175 A | 42.0 kW | 50.4 kW |
| 2/0 | 200 A | 48.0 kW | 57.6 kW |
| 3/0 | 230 A | 55.2 kW | 66.2 kW |
| 4/0 | 270 A | 64.8 kW | 77.8 kW |
Frequently Asked Questions
Common questions about kW to amps conversion and electrical calculations.
For single phase: I = P × 1000 / (V × PF). For three phase: I = P × 1000 / (V × PF × √3). Where I is current in amps, P is power in kW, V is voltage, and PF is the power factor (typically 0.8–0.95). Add efficiency for motor loads: I = P × 1000 / (V × PF × efficiency).
Power factor (PF) is the ratio of real power (kW) to apparent power (kVA), ranging from 0 to 1. It indicates how effectively electrical power is converted into useful work. A PF of 0.85 means 85% of the current does useful work; the rest is reactive power. Most industrial loads have PF between 0.8 and 0.95.
Single-phase uses one voltage waveform and is common in residential settings (120V/240V). Three-phase uses three waveforms offset by 120°, delivering more power efficiently and is used in industrial and commercial settings (208V, 480V, 600V). Three-phase requires less conductor material for the same power and provides smoother power delivery for motors.
Power factor accounts for the phase difference between voltage and current in AC circuits. Without PF correction, you'd underestimate the actual current draw. For example, a 10 kW load at 240V single-phase draws 41.7 A at PF=1.0, but 52.1 A at PF=0.8 — 25% more current for the same real power.
Efficiency (typically 85–95%) accounts for energy losses in motors. A 90% efficient motor draws more current than an ideal motor for the same output power. The formula becomes I = (P × 1000) / (V × PF × efficiency). Input power = output power / efficiency, so lower efficiency means higher current.