Calculate transformer kVA, primary amps, secondary amps, voltage ratio, turns ratio, load percentage, efficiency, losses, and sizing estimates. This calculator works for single-phase and three-phase transformer planning.
kVA and amps:
The calculator converts transformer kVA into primary and secondary amps using voltage and phase type.
Load sizing:
Load watts or kVA can be adjusted by power factor and sizing margin to estimate a transformer size.
Ratio and efficiency:
The calculator also estimates voltage ratio, turns ratio, transformer efficiency, losses, and loss cost.
A transformer calculator helps estimate transformer current, capacity, load percentage, and voltage ratio before selecting or checking a transformer.
It can help with step-down transformers, step-up transformers, control transformers, isolation transformers, distribution transformers, panel planning, machine loads, and service load estimates.
Your result shows transformer kVA, primary amps, secondary amps, primary voltage, secondary voltage, voltage ratio, turns ratio, load percentage, recommended kVA, efficiency, losses, monthly loss cost, and comparison load estimates.
For single-phase, multiply kVA by 1,000 and divide by volts. For three-phase, divide by √3 times volts.
Transformers are rated in apparent power because their heating depends on voltage and current, while the real power depends on the connected load power factor.
Divide the connected load kVA by the transformer rated kVA, then multiply by 100.
No. This calculator gives planning estimates. Final transformer selection must follow equipment nameplates, electrical code, conductor sizing, overcurrent protection, temperature rating, enclosure type, grounding, and manufacturer instructions.