Transformer kVA Calculator

Inputs

Phase

Single-phase uses V x I / 1000. Three-phase uses sqrt(3) x line-to-line voltage x line current / 1000.

Input basis

Calculate from volts and amps, or from real power and power factor.

Load voltage (V)

Line-to-line voltage for three-phase loads, or winding/load voltage for single-phase.

Load current (I)

Line current in amperes.

Power factor (PF)

Used to convert kW to kVA and to estimate real kW when amps are entered.

Sizing margin (M)

Extra capacity before rounding to the next listed standard size.

Default result

Recommended standard size(S_std)

75kVA

Pass

next listed three-phase size

Also computed

Design kVA with margin(S_design)62.35kVA

Load kVA(S_load)49.88kVA

Standard-size full-load current(I_fl)90.21A

Load current(I_load)60A

Standard-size utilization(U)66.51%

Spare capacity vs load(S_spare)25.12kVA

Method notes 2 notes

Three-phase kVA uses sqrt(3) x line-to-line volts x line current / 1000.
This is a transformer apparent-power screen. Final selection still needs continuous-load rules, inrush, motor starting, harmonic heating, impedance, enclosure, temperature rise, primary/secondary protection and local code review.