**Voltage regulation** is the difference between no load voltage and full load voltage by no load voltage.

Voltage regulation = No load voltage – Full load voltage / No load voltage.

Voltage regulation is mentioned in % (percentage).

% Voltage regulation = No load voltage – Full load voltage * 100 / No load voltage.

**Efficiency** of a transformer is the ratio of output in watts and input in watts.

Efficiency = Output in watts / Input in watts.

% Efficiency = Output in watts * 100 / Input in watts.

% Efficiency = Output in watts * 100 / Output in watts + losses.