Enter the supply input power (watts) and the unit output power (watts) into the calculator to determine the Power Supply Efficiency. 

Power Supply Efficiency Formula

The following formula is used to calculate the Power Supply Efficiency. 

Eps = OP / IP * 100

  • Where Eps is the Power Supply Efficiency (%)
  • OP is the supply input power (watts) 
  • IP is the unit output power (watts) 

How to Calculate Power Supply Efficiency?

The following two example problems outline how to calculate the Power Supply Efficiency.

Example Problem #1:

  1. First, determine the supply input power (watts). In this example, the supply input power (watts) is given as 60.
  2. Next, determine the unit output power (watts). For this problem, the unit output power (watts) is given as 100.
  3. Finally, calculate the Power Supply Efficiency using the equation above: 

Eps = OP / IP * 100

Inserting the values from above and solving the equation: 

Eps = 60 / 100 * 100 = 60 (%)


Example Problem #2: 

Using the same process as above, first define the variables required by the formula. In this case, these values are:

supply input power (watts) = 50

unit output power (watts) = 200

Entering these values yields:

Eps = 50 / 200 * 100 = 25 (%)