Three Phase Current Calculator

Work out three phase current instantly with clear inputs, formula shown and shareable results.

About Three Phase Current Calculator

For a balanced three-phase load, P = sqrt(3) x VL x IL x power factor, so line current is apparent power divided by sqrt(3) times line voltage. Efficiency must be applied first when the quoted power is mechanical output, since the supply must provide the losses too.

Formula

Three-phase power

P = sqrt(3) x V x I x pf; I = kVA x 1000 / (sqrt(3) x V)

Worked example

With the default values below, Three Phase Current Calculator returns Line current of 27.69. Change any input above and every figure here is recalculated in your browser.

Inputs used

Load power: 15 kW
Line-to-line voltage: 400 V
Power factor: 0.85
Efficiency: 92 %

Results

Line current: 27.69 A
Apparent power: 19.18 kVA
Electrical input power: 16.30 kW
Reactive power: 10.10 kVAr

Step by step

1Values used
2Three-phase power
3Line current= 27.69 A
4Apparent power= 19.18 kVA
5Electrical input power= 16.30 kW
6Reactive power= 10.10 kVAr

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Where does sqrt(3) come from?

It is the ratio between line and phase quantities in a three-phase system, arising from the 120 degree phase displacement between the windings.

Why does poor power factor raise current?

Real power is fixed by the load, so a lower power factor means more apparent power and therefore more current for the same useful output — and more I squared R loss in the cables.