Convert balanced three-phase line voltage, current and power factor into apparent (kVA), real (kW) and reactive (kvar) power plus the phase angle.
For design guidance only. Always verify with a qualified engineer.
About this three-phase power converter
This free three-phase power converter turns the measured line quantities of a balanced three-phase load: line-to-line voltage, line current and power factor, into apparent power (kVA), real power (kW), reactive power (kvar) and the phase angle. It is aimed at electrical designers, contractors and facilities engineers sizing supplies, transformers, generators and power-factor correction at tender or verification stage. Everything runs in your browser. Nothing is uploaded.
How three-phase power is calculated
For a balanced three-phase load the line relations are S = √3 × VL × IL for apparent power, P = S × cosφ for real power, and Q = √(S² − P²) for reactive power, where the phase angle is φ = acos(cosφ). The √3 (≈ 1.732) factor comes from the 120° displacement between the three phases when working from line-to-line voltage and line current. The default line voltage of 400 V is the line value of the standard IEC 60038 230/400 V low-voltage system. Results follow the standard power triangle, so apparent, real and reactive power satisfy S² = P² + Q².
Frequently asked questions
Should I enter line or phase voltage?
Enter the line-to-line (phase-to-phase) voltage: 400 V on a standard UK LV supply. The √3 factor in S = √3 × VL × IL already accounts for the line-to-phase geometry, so you do not need to convert to phase voltage first.
What does the power factor change?
Power factor (cosφ) is the ratio of real power to apparent power. At a power factor of 1 the load is purely resistive, so reactive power Q is zero and the phase angle is 0°. As the power factor falls, more of the apparent kVA is reactive kvar, which is why poor power factor needs larger cables, switchgear and transformers for the same useful kW.
Does this work for an unbalanced load?
No: the √3 line relations assume a balanced three-phase load, where each phase carries equal current at the same power factor. For a significantly unbalanced load you should analyse each phase separately and sum the per-phase powers.