kVA to Amps Calculator
This kVA to amps calculator converts kVA to amps for single-phase and three-phase systems. Enter the apparent power in kVA and the voltage, and the kVA to amps calculator returns the current in amperes to size cables, breakers, and generators. It applies the kVA to amps formula three phase automatically.
Results
The kVA to Amps Calculator is part of our AC & Three Phase collection. Browse more ac & three phase to size, convert, and check your work alongside this tool.
What the kVA to amps calculator does
The kVA to amps calculator turns an apparent power rating into the current a circuit will carry. Equipment like transformers and generators is rated in kVA, but cable and breakers are rated in amps, so to convert kVA to amps is the everyday install-side question. This kVA to amps calculator covers single-phase and three-phase, applying the kVA to amps formula three phase so you get the correct current every time.
kVA to amps formula
To convert kVA to amps, divide the apparent power by the voltage. Single-phase and three-phase differ by the √3 factor:
The kVA to amps formula three phase includes √3 (about 1.732) because power is shared across three conductors, which is the heart of the kVA to ampere calculation.
kVA to amps example
A 10 kVA three-phase transformer on a 400 V system, through the kVA to amps formula three phase:
The same 10 kVA on a single-phase 230 V supply draws about 43.5 A. For a large rating, 1000 kVA to amps at 400 V three-phase is about 1443 A.
How to use the kVA to amps calculator
Pick single-phase or three-phase, enter the apparent power in kVA, then the voltage. The kVA to amps calculator returns the full-load current in amperes. For any three phase kVA to amps job, use the line-to-line voltage and the kVA to ampere calculation applies the √3 factor for you.
Reading the kVA to amps result
The result is the full-load current. Size conductors and protection above this value, adding the margins your electrical code requires and extra allowance for motor starting or transformer inrush. Three-phase delivers the same power at a much lower per-conductor current, which is why the three phase kVA to amps figure is roughly a third of the single-phase one.
When to convert kVA to amps
- Sizing cables and breakers from a kVA to amps calculation
- Finding full-load current with the kVA to amps formula three phase
- Checking a 1000 kVA to amps figure for a large transformer
- Selecting a generator or UPS with the kVA to ampere calculation
Common kVA to amps mistakes
- Using phase voltage for three-phase. Always enter line-to-line voltage in the kVA to amps calculator.
- Treating kVA as kW. kVA is apparent power; real power needs the power factor.
- Forgetting inrush. Motors and transformers draw far more than full-load current at startup.
Tips for accurate kVA to amps results
- Use line-to-line voltage for every three phase kVA to amps calculation.
- Add code margins and starting allowances to the current.
- Prefer three-phase for large loads to keep conductor sizes manageable.
Why kVA to amps is the install-side question
Most people reach for a kVA to amps calculator at the point of installation, because equipment arrives rated in kVA but must be wired with cable and breakers rated in amps. A transformer nameplate says 500 kVA; the electrician needs the current to size the feeder, so they convert kVA to amps. This is the reverse of the design-side amps to kVA question, and a good kVA to amps calculation answers it without rearranging a formula by hand.
Why three-phase changes the kVA to ampere calculation
The kVA to amps formula three phase includes √3 because power is delivered across three conductors offset by 120 degrees. The same apparent power arrives at a lower current per conductor, so a three phase kVA to amps conversion of a large rating like 1000 kVA gives a far smaller current than the single-phase equivalent. This is exactly why industrial sites use three-phase for big loads, and why the kVA to amps chart shows the three-phase column running about a third of the single-phase current.
kVA to amps chart
A quick kVA to amps chart for common ratings, single-phase (230 V) and three-phase (400 V):
| kVA | Amps @230V 1-phase | Amps @400V 3-phase |
|---|---|---|
| 1 kVA | 4.3 A | 1.4 A |
| 10 kVA | 43.5 A | 14.4 A |
| 100 kVA | 435 A | 144 A |
| 1000 kVA | 4348 A | 1443 A |
kVA to Amps Calculator FAQ
How do I convert kVA to amps?
Divide kVA times 1000 by the voltage. For three-phase, divide by √3 times the voltage. The kVA to amps calculator applies this kVA to amps formula three phase automatically.
What is the kVA to amps formula for three phase?
Current equals kVA times 1000 divided by (√3 times the line-to-line voltage). This kVA to amps formula three phase is what the calculator uses when you select three-phase.
How many amps is 1000 kVA?
At 400 V three-phase, 1000 kVA to amps is about 1443 A; at 230 V single-phase it is around 4348 A. See the kVA to amps chart above, or run the exact figure.
What voltage do I use for three-phase?
Use the line-to-line voltage, such as 400 V. The kVA to ampere calculation includes the √3 factor, so entering line-to-line voltage gives the correct current.