kVA to amps calculator

Convert between kVA, kW and amps for three-phase, single-phase and DC circuits at any voltage. Enter what you know and get the current, apparent, active and reactive power. Free, no signup.

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Circuit
System
V

Line-to-line for three-phase (e.g. 400 V or 11000 V), line-to-neutral for single-phase (e.g. 230 V).

About 0.8 for generator and transformer ratings, 0.85–0.9 for motors at full load.

Convert from
I know the
kVA
kW
A

Current I

—

Formula: —

Check the inputs: a positive voltage and value, and a power factor between 0 and 1.

Current I
—
Apparent power S
—
Active power P
—
Reactive power Q
—
Rule of thumb at this voltage
—

Balanced load. For three-phase circuits the result is the line current: the current in each cable conductor.

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How the conversion works

The current follows from the apparent power and the voltage. The power factor links apparent power (kVA) and active power (kW).

  1. Three-phase ACI = S / (√3 · U) = P / (√3 · U · cos φ)U is the line-to-line voltage.
  2. Single-phase ACI = S / U = P / (U · cos φ)
  3. DCI = P / U
  4. Power triangleP = S · cos φ,  Q = S · sin φ,  S² = P² + Q²

Use volts with VA and W, or kilovolts with kVA and kW: the units cancel the same way.

Worked examples

100 kVA at 400 V, three-phase144.3 A
55 kW at 400 V, three-phase, cos φ = 0.988.21 A
32 A at 230 V, single-phase7.36 kVA
2.4 kW at 48 V DC50 A

For a motor, the nameplate kW is the shaft power, so divide by the efficiency as well: a 55 kW motor with 94 % efficiency draws about 93.8 A at 400 V and cos φ = 0.9.

Amps per kVA at common voltages

Current in amperes for a balanced load: I = S / (√3 · U) for three-phase, S / U for single-phase.
Voltage1 kVA10 kVA100 kVA1000 kVA
230 V single-phase4.34843.48434.84,348
400 V three-phase1.44314.43144.31,443
415 V three-phase1.39113.91139.11,391
480 V three-phase1.20312.03120.31,203
690 V three-phase0.83678.36783.67836.7
11 kV three-phase0.05250.52495.24952.49
20 kV three-phase0.02890.28872.88728.87
33 kV three-phase0.01750.17501.75017.50

For a transformer, the rated kVA gives the full-load current on each side. The transformer full-load current calculator lists the standard sizes.

Get these formulas and more in a free two-page PDF cheat sheet

Frequently asked questions

How many amps is 1 kVA?

It depends on the voltage. At 400 V three-phase, 1 kVA is 1.443 A; at 480 V three-phase, 1.203 A; at 230 V single-phase, 4.348 A. Divide 1000 by √3 times the line-to-line voltage for three-phase, or by the voltage for single-phase.

What is the difference between kVA and kW?

kVA is apparent power, the product of voltage and current. kW is active power, the part that does useful work: kW = kVA × power factor. Cables, transformers and generators are rated in kVA because their heating depends on the current, whatever the power factor.

How do I convert kW to amps?

Divide the power in watts by √3 × U × cos φ for three-phase, or by U × cos φ for single-phase, with U in volts. For a motor, divide the nameplate kW (shaft power) by the efficiency first.

Why is there a √3 in the three-phase formula?

A balanced three-phase load takes three times the power of one phase: S = 3 · Uphase · I. With the line-to-line voltage U = √3 · Uphase, this becomes S = √3 · U · I.

Is the result the line current or the phase current?

The line current, which flows in each cable conductor. In a star-connected load it equals the phase current; in a delta-connected load the current in each branch is the line current divided by √3.

Keep learning

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