⚡ Transformer Sizing Calculator

Determine the correct kVA rating for your electrical load. Ensure safe and efficient power distribution.

✅ Formula verified against standard references Last Updated: Jan 2026

Required Capacity

14.4 kVA
Recommended Size:
15 kVA

💡 Expert Tips

Don't forget the Power Factor. If you are sizing a generator or transformer for motors, the Power Factor (PF) matters. kVA = kW / PF. If you only know the kW (horsepower) of your motor, assume a PF of 0.8 to be safe.

Standard Sizes. Transformers don't come in every size. Common single-phase sizes are 10, 15, 25, 37.5, 50, 75, 100 kVA. Common 3-phase sizes are 15, 30, 45, 75, 112.5, 150, 225 kVA. Always round up to the next standard size.

Primary vs Secondary. This calculator sizes the transformer based on the LOAD (Secondary side). Ensure your primary supply voltage matches the transformer's primary rating (e.g., 480V Primary -> 240V Secondary).

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