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Line To Phase Voltage Calculator

Work out line to phase voltage instantly with clear inputs, formula shown and shareable results.

About Line To Phase Voltage Calculator

In a star-connected system the phase voltage is the line voltage divided by sqrt(3): 400 V between lines gives 230 V to neutral. Both voltages describe the same supply, which is why a three-phase distribution board offers single-phase 230 V outlets and three-phase 400 V circuits from the same cable.

Formula

Star relationships

Vphase = Vline / sqrt(3); S = sqrt(3) x Vline x Iline

Worked example

With the default values below, Line To Phase Voltage Calculator returns Phase (line-to-neutral) voltage of 230.94. Change any input above and every figure here is recalculated in your browser.

Inputs used

Line-to-line voltage
400 V
Line current
22 A
Power factor
0.9

Results

Phase (line-to-neutral) voltage
230.94 V
Three-phase real power
13.72 kW
Power per phase
4.57 kW
Apparent power
15.24 kVA

Step by step

  1. 1Values used
  2. 2Star relationships
  3. 3Phase (line-to-neutral) voltage= 230.94 V
  4. 4Three-phase real power= 13.72 kW
  5. 5Power per phase= 4.57 kW
  6. 6Apparent power= 15.24 kVA

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges 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

Is it the same in a delta connection?

No. In delta the phase voltage equals the line voltage, but the line current is sqrt(3) times the phase current.

Why 400 V and 230 V together?

They are the same system: 230 V is measured line to neutral and 400 V line to line, since 230 x sqrt(3) = 398 V.

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