Enter the linear regulator input (watts) and the linear regulator output (watts) into the calculator to determine the Linear Regulator Efficiency. 

Linear Regulator Efficiency Formula

The following formula is used to calculate the Linear Regulator Efficiency. 

Elr = RO/ RI *100
  • Where Elr is the Linear Regulator Efficiency (%)
  • RI is the linear regulator input (watts) 
  • RO is the linear regulator output (watts) 

To calculate the linear regulator efficiency, divide the regulator output by the regulator input, then multiply by 100.

How to Calculate Linear Regulator Efficiency?

The following two example problems outline how to calculate the Linear Regulator Efficiency.

Example Problem #1:

  1. First, determine the linear regulator input (watts). In this example, the linear regulator input (watts) is given as 30.
  2. Next, determine the linear regulator output (watts). For this problem, the linear regulator output (watts) is given as 25.
  3. Finally, calculate the Linear Regulator Efficiency using the equation above: 

Elr = RO/ RI *100

Inserting the values from above and solving the equation: 

Elr = 25/ 30 *100 = 83.334 (%)


What factors can affect the efficiency of a linear regulator?

The efficiency of a linear regulator is primarily affected by the difference between the input and output voltage, the load current, and the quiescent current of the regulator itself. Higher differences between input and output voltage, as well as higher load currents, typically result in lower efficiency.

Can the efficiency of a linear regulator be improved?

While the basic principle of a linear regulator inherently limits its maximum efficiency, certain design choices can help improve it. Using a linear regulator with a lower dropout voltage, minimizing the difference between input and output voltage, and choosing a regulator with a lower quiescent current can help improve efficiency.

Why would one choose a linear regulator over a more efficient switching regulator?

Despite their lower efficiency, linear regulators are often chosen for their simplicity, low noise output, and fast response to load changes. They are particularly favored in applications where power efficiency is less critical than noise-sensitive analog circuits, such as audio amplifiers or RF circuits.