Transformer Current Calculator

Convert Transformer kVA ratings to Full Load Amperage (FLA) for electrical sizing.

Phase

Transformer Rating (kVA)

Primary Voltage (V)

Secondary Voltage (V)

Full Load Amperage (FLA)

0 Amps

How to Calculate Transformer Amperage

To properly size circuit breakers, fuses, and electrical wiring, engineers must calculate the Full Load Amperage (FLA) on both the primary (high voltage) and secondary (low voltage) sides of a transformer.

1-Phase Formula: $$ I = \frac{kVA \times 1000}{V} $$
3-Phase Formula: $$ I = \frac{kVA \times 1000}{V \times \sqrt{3}} $$

Where $I$ is Current in Amperes, $kVA$ is the transformer power rating, and $V$ is the line-to-line voltage.