In practice change in input voltage to a voltage regulator will cause a charge in its output or load voltage. The line regulation (source regulation) indicates the change in outputthat will occur due to change in input voltage.

It is defined as the change in regulated load voltage due to change in line voltage (input voltage) in specified range.

It is given by,
$S.R=V_{LH}-V_{LL}$

Where,

VLH = load voltage with highest line voltage

VLL= load voltage with lowest line voltage

The percent line regulation is given by,

%S.R.=S.R./$V_{NOM}\times 100$

Where,

VNom = Nominal Load Voltage

B) Load Regulation

In practice, voltage regulator will change output voltage when there is a change in load current.

The load regulation indicates the change in output voltage occurring due to change in load current.

The load regulation is defined as the change in output voltage when load current is changed from zero (no load) to maximum (full load) values

L.R.=$V_{NL}-V_{FL}$

Where,

VNL = output voltage on no load

VFL = output on full load

Also,

%L.R.=$V_{NL}-V_{FL}/V_{FL}\times 100$