Calculate transformer kVA from volts and amps, watts and power factor, or load current. This calculator helps estimate single-phase and three-phase transformer size, primary amps, secondary amps, load percentage, recommended kVA, and remaining capacity.
Volts and amps:
The calculator uses voltage, current, and phase type to estimate transformer kVA.
Watts and power factor:
When using watts, the calculator divides by power factor to estimate apparent power.
Recommended size:
The calculated load is adjusted by margin and continuous load factor, then rounded up to a common transformer size.
A transformer kVA calculator helps estimate the transformer size needed for a load before selecting equipment.
It can help with step-down transformers, step-up transformers, control transformers, isolation transformers, distribution transformers, panel loads, machine loads, and service planning.
Your result shows calculated kVA, recommended transformer kVA, primary amps, secondary amps, load amps, load watts, load percentage, remaining kVA, remaining percentage, sizing margin, and comparison load estimates.
For single-phase, multiply volts by amps and divide by 1,000. For three-phase, multiply √3 by volts and amps, then divide by 1,000.
Divide watts by 1,000 times the power factor. For example, 54,000 watts at 0.90 power factor is 60 kVA.
Yes. Transformer sizing is usually rounded up to the next standard transformer size, especially when margin or future load is needed.
No. This calculator gives a planning estimate. Final transformer sizing must follow electrical code, load type, duty cycle, temperature, conductor sizing, overcurrent protection, and manufacturer instructions.