kVA to Amps Calculator
Find current directly from apparent power and line voltage for single and three-phase systems.
How do you convert kVA to amps?
For single-phase, amps = (kVA × 1000) ÷ V. A 10 kVA single-phase supply at 240 V gives (10 × 1000) ÷ 240 = 41.7 A. For three-phase, amps = (kVA × 1000) ÷ (√3 × V): a 10 kVA, 400 V three-phase supply gives 10000 ÷ (1.732 × 400) = 14.4 A.
kVA to Amps Formula
Multiply kVA by 1,000 to convert to VA (volt-amps), then divide by the line voltage. This gives the current in amps for a single-phase system. Example: 5 kVA at 120 V to (5,000) ÷ 120 = 41.67 A.
For three-phase, divide by voltage and the square root of 3 (≈ 1.7321). The √3 factor arises from the 120° phase angle between conductors. Use line-to-line voltage (e.g. 400 V, 480 V). Example: 5 kVA at 400 V to 5,000 ÷ (400 × 1.7321) = 7.22 A.
kVA to Amps Reference Table — Single-phase
| kVA | Amps @ 120 V | Amps @ 240 V |
|---|---|---|
| 1 kVA | 8.3333 A | 4.1667 A |
| 2 kVA | 16.6667 A | 8.3333 A |
| 5 kVA | 41.6667 A | 20.8333 A |
| 10 kVA | 83.3333 A | 41.6667 A |
| 20 kVA | 166.6667 A | 83.3333 A |
| 50 kVA | 416.6667 A | 208.3333 A |
Single-phase vs Three-phase
One live conductor plus a neutral. Power is delivered as a single sinusoidal wave. Common in homes, small offices, and retail units up to around 10 kVA. Higher current per conductor for the same power.
A = (kVA × 1,000) ÷ VThree live conductors, each offset 120° apart. Delivers three times the power at the same current, making it ideal for motors, data centres, and industrial sites. Far more efficient for loads above 10 kVA.
A = (kVA × 1,000) ÷ (V × √3)Transformer and Generator Output Limits
When selecting a transformer or generator rated in kVA, converting to amps is the only way to know what size breaker you need and how many circuits it can feed. Here are standard equipment examples:
- 22 kVA Standby Generator (240 V Single-Phase):
Amps = (22 × 1,000) ÷ 240 = 91.6 A. This unit pairs perfectly with a 100 Amp automatic transfer switch (ATS) to back up a standard residential subpanel. - 75 kVA Distribution Transformer (208 V Three-Phase):
Amps = (75 × 1,000) ÷ (208 × 1.732) = 208 A. This is exactly why 75 kVA is the standard transformer size used to feed a 200 Amp commercial electrical panel. - 500 kVA Pad-Mount Transformer (480 V Three-Phase):
Amps = (500 × 1,000) ÷ (480 × 1.732) = 601 A. Common for medium-sized factories; typically feeds a 600 Amp main switchgear lineup.
Frequently Asked Questions
Multiply kVA by 1,000 and divide by the voltage. For
single-phase: A = (kVA × 1,000) ÷ V.
For three-phase: A = (kVA × 1,000) ÷ (V × √3).
For example, 10 kVA at 240 V single-phase gives
(10 × 1,000) ÷ 240 = 41.67 A.
- Single-phase:
A = (kVA × 1,000) ÷ V - Three-phase:
A = (kVA × 1,000) ÷ (V × √3), where √3 ≈ 1.7321
Note that kVA is apparent power — it does not account for power factor, unlike kW (real power). Use kVA when sizing cables, fuses, and switchgear.
- Single-phase at 240 V: (5 × 1,000) ÷ 240 = 20.83 A
- Three-phase at 240 V (L-L): (5 × 1,000) ÷ (240 × 1.7321) = 12.03 A
Three-phase draws less current per conductor because load is shared across three wires.
Single-phase power uses one live conductor and a neutral, delivering power as a single sinusoidal wave. It is standard in homes and small offices. Three-phase power uses three live conductors, each carrying a wave offset by 120°. For the same kVA, three-phase requires significantly less current per conductor, making it more efficient for large motors, industrial equipment, and commercial buildings.
Does power factor affect the amp output of a kVA-rated transformer?
No. The apparent power (kVA) dictates the physical current (Amps) flowing through the wires. A 10 kVA transformer at 240V can provide a maximum of 41.6 Amps, regardless of whether the load has a power factor of 1.0 or 0.5. Low power factor just means those 41.6 Amps will do less useful work (kW).