Enter the transformer output power (watts) and the total power losses (watts) into the calculator to determine the Transformer Efficiency. 

Transformer Efficiency Formula

The following formula is used to calculate the Transformer Efficiency. 

Et = Po / (Po + PL) *100

  • Where Et is the Transformer Efficiency (%)
  • Po is the transformer output power (watts) 
  • PL is the total power losses (watts) 

How to Calculate Transformer Efficiency?

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

Example Problem #1:

  1. First, determine the transformer output power (watts). In this example, the transformer output power (watts) is given as 50.
  2. Next, determine the total power losses (watts). For this problem, the total power losses (watts) is given as 5.
  3. Finally, calculate the Transformer Efficiency using the equation above: 

Et = Po / (Po + PL) *100

Inserting the values from above and solving the equation: 

Et = 50 / (50 + 5) *100 = 90.909 (%)


Example Problem #2: 

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

transformer output power (watts) = 60

total power losses (watts) = 7

Entering these values yields:

Et = 60 / (60 + 7) *100 = 89.55 (%)