Transformer Calculator

Select the number of phases and enter the transformer rating, primary voltage, and secondary voltage. The calculator will evaluate and display the primary and secondary full-load current along with the turns ratio.

Transformer Formula

The following formulas are used to calculate the primary and secondary full-load currents.

Single phase full load = tr * 1000 / v

three phase full load = tr * 1000/ (1.73 * V)

  • Where tr is the transformer rating
  • v is the voltage (either primary or secondary)

The following formula is used to calculate the transformer turns ratio.

Turns Ratio = I2/I1

  • Where I1 is the primary current
  • I2 is the secondary current

Transformer Definition

A transformer is a static electrical machine that transfers AC electrical current between two more more circuits.

Transformer Example

How to calculate turns ratio?

  1. First, determine the value of the primary current.

    Measure the primary current.

  2. Next, determine the value of the secondary current.

    Measure the secondary current.

  3. Finally, calculate the turns ratio.

    Calculate the turns ratio using the formula above.


What is a turns ratio?

A turns ratio is a ratio of the primary current to the secondary current of a transformer.

transformer calculator