Transformer loading calculator
Compare a load’s apparent power with a transformer’s nameplate kVA rating. This is a loading ratio, not a thermal approval.
Educational reference only. Examples and calculator results are not approved installation designs, equipment selections or operating instructions.
Your inputs
Results update as you edit. Use a decimal point. Default values are hypothetical, not recommended equipment sizes.
Electrical input or load power, not motor shaft output.
Enter a positive power factor up to 1, for example 0.9.
Use apparent-power kVA, not an assumed kW rating.
Illustrative result
- Nameplate loading ratio
- 66.667 %
- Load apparent power
- 666.667 kVA
A ratio at or below 100% does not establish safe loading; cooling, harmonics and manufacturer limits still matter.
Worked steps
- Sload = 600 / 0.9 = 666.667 kVA
- Loading = 100 × 666.667 / 1,000 ≈ 66.667%
Calculations use unrounded values; displayed steps are rounded to three decimal places or five significant digits for extreme values.
Formula and units
Sload (kVA) = P / PF; loading (%) = 100 × Sload / Srated
Change one input to see its effect. Inputs are calculated in your browser and are not submitted to a calculation service.