kVA is apparent power - the product of RMS voltage and RMS current without any power factor adjustment. Converting kVA to amps is just rearranging that definition, so PF is not needed. PF only matters when you cross over to kW (real power).

Which voltage do I use?

Use the voltage on the side you want amps for. A 480V/208V transformer has different primary and secondary FLA - use 480 V for primary amps, 208 V for secondary amps.

Does this work for generators?

Yes. Generator nameplates list kVA capacity at a specific voltage and phase. Apply the same formula. Note that generators also have a kW rating (kVA × power factor) which limits the real power they can sustain.

kVA to Amps Calculator

Convert kVA to amps for single-phase and three-phase circuits. Free electrical calculator for electricians.

Inputs

Apparent Power

kVA

Voltage

Phase

Single-PhaseThree-Phase

Result

Current

83.33A

I = (kVA × 1000) / V = (10 × 1000) / 120

About this calculator

Transformers, generators, and UPS equipment are rated in kVA because that rating is set by the heat the equipment can dissipate, which depends on apparent power - not real power. To wire the equipment you need amps. Converting kVA to amps needs voltage and the system phase configuration; no power factor needed because kVA already includes it.

Formula

Single-phase amps equal kVA times 1000 divided by voltage. Three-phase divides by √3 times line-to-line voltage instead.

Single-phase: I = (kVA × 1000) ÷ V
Three-phase: I = (kVA × 1000) ÷ (√3 × V_LL)

How to use

Pick single-phase or three-phase.
Enter the kVA rating from the nameplate.
Enter the voltage on the side you want amps for (primary or secondary).
Read the resulting full-load amps.

Worked example

Setup

A 75 kVA, 480V to 208Y/120V three-phase transformer. Find primary and secondary FLA.

Calculation

Primary: I = (75 × 1000) ÷ (1.732 × 480) = 75,000 ÷ 831.4 = 90.2 A. Secondary: I = (75 × 1000) ÷ (1.732 × 208) = 75,000 ÷ 360.3 = 208.2 A.

Answer

Primary FLA is 90.2 A, secondary FLA is 208.2 A. Use these for sizing primary and secondary conductors and OCPD per NEC 450.3.

Frequently asked questions

Why no power factor?: kVA is apparent power - the product of RMS voltage and RMS current without any power factor adjustment. Converting kVA to amps is just rearranging that definition, so PF is not needed. PF only matters when you cross over to kW (real power).
Which voltage do I use?: Use the voltage on the side you want amps for. A 480V/208V transformer has different primary and secondary FLA - use 480 V for primary amps, 208 V for secondary amps.
Does this work for generators?: Yes. Generator nameplates list kVA capacity at a specific voltage and phase. Apply the same formula. Note that generators also have a kW rating (kVA × power factor) which limits the real power they can sustain.