Enter the total energy output (J) and the total energy input (J) into the Return on Energy Invested Calculator. The calculator will evaluate and display the Return on Energy Invested. 

Return on Energy Invested Formula

The following formula is used to calculate the Return on Energy Invested. 

EROI = EO / EI * 100

  • Where EROI is the Return on Energy Invested (%)
  • EO is the total energy output (J) 
  • EI is the total energy input (J) 

How to Calculate Return on Energy Invested?

The following example problems outline how to calculate Return on Energy Invested.

Example Problem #1:

  1. First, determine the total energy output (J). 
    • The total energy output (J) is given as: 175.
  2. Next, determine the total energy input (J). 
    • The total energy input (J) is provided as: 350.
  3. Finally, calculate the Return on Energy Invested using the equation above: 

EROI = EO / EI * 100

The values given above are inserted into the equation below and the solution is calculated:

EROI = 175 / 350 * 100 = 50 (%)


Example Problem #2: 

For this problem, the variables needed are provided below:

total energy output (J) = 600

total energy input (J) = 800

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

EROI = EO / EI * 100 = ?