kVA to Amps Calculator

How it is calculated

Apparent power in kVA is multiplied by 1000 to get volt-amperes and divided by the voltage. For a single-phase supply the formula is I = kVA × 1000 / V; for a three-phase supply it is I = kVA × 1000 / (√3 × V), with √3 ≈ 1.732. I is the line current in amperes and V is the voltage in volts: phase-to-neutral for single phase, line-to-line (for example 400 V) for three phase. Phase is single unless three-phase is chosen. The voltage must be above zero and the kVA cannot be negative. The result is rounded to two decimals. Power factor is not an input: kVA already includes it, so the answer is the total current the conductors carry, not only the part doing useful work.

Common mistakes

• Leaving the phase on single for a three-phase machine. At 400 V the same 50 kVA gives 125.00 A instead of 72.17 A, so cables and breakers would be sized far too big.
• Using the phase-to-neutral voltage (230 V) in the three-phase formula. The √3 already accounts for the phase relationship, so enter the line-to-line voltage, here 400 V.
• Entering kW instead of kVA. A kW rating is real power; dividing by the power factor gives kVA, and a load at 0.8 power factor draws a quarter more current than the kW figure suggests.
• Typing the power in VA or MVA. The field takes kVA, so 50 000 VA must be entered as 50 and 0.5 MVA as 500.
• Treating the result as a breaker rating. It is the rated full-load current; breakers, cables and starting currents need extra margin and local code rules.