Amps to kVA calculator
Pick the direction, enter the values, and choose single or three phase. Line-to-line voltage is what you enter for three phase, which is 400 volts on a European supply and 480 on a US industrial one.
- Apparent power
- 69.28 kVA
Three phase uses the square root of three (1.732) as the line factor.
The formulas
Single phase: kVA = V x A / 1,000, and A = kVA x 1,000 / V.
Three phase: kVA = 1.732 x V x A / 1,000, and A = kVA x 1,000 / (1.732 x V), where V is line-to-line voltage.
kW to amps needs power factor: A = kW x 1,000 / (V x PF) single phase, or A = kW x 1,000 / (1.732 x V x PF) three phase. Motors and transformers run at 0.8 to 0.9 power factor; heaters and incandescent lighting at 1.0.
The 1.732 is the square root of three, and it appears because three-phase power is delivered across three conductors whose voltages are 120 degrees apart.
Common transformer and generator sizes
These are full-load line currents for standard kVA ratings. Use them to check a cable or breaker size against a transformer or generator nameplate.
| kVA | 208 V | 400 V | 480 V |
|---|---|---|---|
| 15 | 41.6 | 21.7 | 18.0 |
| 30 | 83.3 | 43.3 | 36.1 |
| 45 | 124.9 | 65.0 | 54.1 |
| 75 | 208.2 | 108.3 | 90.2 |
| 112.5 | 312.3 | 162.4 | 135.3 |
| 150 | 416.4 | 216.5 | 180.4 |
| 225 | 624.5 | 324.8 | 270.6 |
| 300 | 832.7 | 433.0 | 360.8 |
| 500 | 1,387.9 | 721.7 | 601.4 |
