Voltage Regulation Calculator (with Examples)

Transformer voltage regulation refers to its ability to maintain a constant output regardless of variations in the input voltage or load conditions. It determines how well a transformer can regulate the voltage at its secondary terminals.

This tool calculates both the Step up and Step down voltage regulation


  • VNo-load
  • VFull-load




Step Down Voltage Regulation represents the change in terminal voltage when a load current at any power factor is applied, expressed as a fraction of the no-load terminal voltage.

VRSD = (VNo-load – VFull-load)/VNo-load

Step up voltage regulation represents the ratio of the change in the terminal voltage when a load at a given power factor is removed, and the load voltage.

VRSU = (VNo-load – VFull-load)/VFull-load

Example Calculation

Consider a transformer with a no-load voltage of 120 volts and a full-load voltage of 110 volts.

Using the calculator VRSD = 8.33% and VRSU = 9.09%


Transformer voltage regulation is the measure of the change in voltage from no-load to full-load conditions, expressed as a ratio or percentage of the

  • full-load voltage
  • no load voltage

A lower percentage indicates better voltage regulation and a more stable output voltage. The concept of ideal transformer voltage regulation refers to the scenario where there is no change in voltage from no-load to full-load conditions. In an ideal transformer, the voltage regulation would be zero.

Voltage regulation is crucial in transformers as it ensures a stable and reliable supply of electricity. It allows for secondary devices to receive the required voltage consistently, preventing damage or malfunction due to overvoltage or undervoltage.


[1] Voltage Regulation and Efficiency of Transformers