kVA to Amps Calculator
Convert kVA to amps for single-phase and three-phase systems: enter apparent power and voltage to get the current draw.
How this calculator works
Apparent power in kVA and voltage together determine how much current a circuit draws. This calculator converts kVA into amps, and it handles both single-phase and three-phase systems, which use slightly different formulas.
For single-phase, current is apparent power divided by voltage. For three-phase, the same apparent power is spread across three conductors, so the voltage is multiplied by the square root of three before dividing.
Formula: Single-phase amps = kVA × 1000 ÷ Volts. Three-phase amps = kVA × 1000 ÷ (Volts × √3).
Worked example
A 10 kVA load at 240 V:
- Single-phase: 10000 ÷ 240 ≈ 41.67 A
- Three-phase: 10000 ÷ (240 × 1.732) ≈ 24.06 A
Notes
The three-phase formula uses the square root of three, where √3 ≈ 1.732. This factor comes from the geometry of how the three conductors combine, and it is what separates the two calculations.
For the same apparent power and voltage, three-phase carries the load at a lower current per conductor than single-phase. The same power is simply shared across three paths instead of one, which is why the three-phase current comes out smaller. Lower current per conductor allows thinner wire and smaller equipment for the same delivered power.
How to use
Enter the apparent power in kVA and the system voltage, then choose single-phase or three-phase to match your supply. The calculator returns the current draw in amps, which you can use as a starting point for sizing conductors and protection with an electrician.
Electrical work is code-governed and safety-critical. Confirm circuit, breaker, and conductor sizing with a licensed electrician and your local code.
Frequently asked questions
What is the difference between kVA and kW?
kVA is apparent power, the total power flowing in the circuit, while kW is real power, the part that does useful work. The two are equal only when the power factor is 1. Because kVA counts the full current, it is the right figure to use when converting to amps for sizing wires and breakers.
When do I use the single-phase versus three-phase formula?
Use single-phase for standard home and small-appliance circuits fed by two wires. Use three-phase for larger commercial and industrial equipment fed by three live conductors. The three-phase formula adds a square-root-of-three factor because the three conductors share the load, which lowers the current on each one.
What voltage should I enter?
Use the system voltage the equipment actually runs on. For single-phase, that is the line-to-line or line-to-neutral voltage feeding the load, such as 120 V or 240 V. For three-phase, use the line-to-line voltage, such as 208 V or 480 V. Matching the correct voltage to the correct phase setting is essential for an accurate current figure.
Why does three-phase draw less current for the same kVA?
In a three-phase system the same apparent power is shared across three conductors instead of concentrated in one path. Dividing by the square root of three, about 1.732, accounts for that sharing. The result is a lower current per conductor, which is one reason three-phase is favored for delivering large amounts of power efficiently.
Estimates only. Verify quantities with your supplier before purchasing.