Transformer Sizing Calculator
Calculate transformer KVA rating and current based on load requirements and voltage levels
About this calculator
The Transformer Sizing Calculator helps electrical engineers and technicians determine the proper transformer KVA rating and current values for specific electrical loads. This tool ensures optimal transformer selection by calculating the required capacity based on your load requirements, primary and secondary voltage levels, and safety factors. Proper transformer sizing prevents overloading, reduces energy costs, and ensures reliable electrical system operation while meeting code requirements.
How to use
Enter your total load requirement in watts or kilowatts, then input the primary voltage (supply side) and secondary voltage (load side). The calculator will automatically compute the required transformer KVA rating and current values for both primary and secondary sides, helping you select the appropriate transformer size.
Frequently asked questions
What safety factor should I add to transformer sizing?
Typically add 20-25% safety margin to account for future load growth, power factor variations, and temperature derating requirements.
How do I calculate three-phase transformer requirements?
For three-phase systems, use line-to-line voltages and multiply single-phase calculations by √3 (1.732) for proper sizing.
What's the difference between KVA and KW ratings?
KVA is apparent power including reactive components, while KW is real power. Transformers are rated in KVA capacity.