Enter the mass before fusion (kg) and the mass after fusion (kg) into the calculator to determine the Fusion Energy. 

Fusion Energy Formula

The following equation is used to calculate the Fusion Energy. 

E = (m1-m2)*c^2


  • Where E is the Fusion Energy (Joules)
  • m1 is the mass before fusion (kg) 
  • m2 is the mass after fusion (kg) 
  • c is the speed of light (299792458 m/s)

To calculate the fusion energy, multiply the change in mass by the speed of light squared.

How to Calculate Fusion Energy?

The following two example problems outline the steps and information needed in order to calculate the Fusion Energy.

Example Problem #1:

  1. First, determine the mass before fusion (kg). In this example, the mass before fusion (kg) is measured to be .00000012.
  2. Next, determine the mass after fusion (kg). For this problem, the mass after fusion (kg) is calculated to be .00000008.
  3. Finally, calculate the Fusion Energy using the formula above: 

E = (m1-m2)*c^2

Inserting the values from above and solving the equation with the imputed values gives: 

E = (.00000012-.00000008)*299792458^2 = 3595020714.95 (Joules)

Example Problem #2: 

Using the same process as example problem 1, we first define the needed variables outlined by the formula. In this case, the values are provide as: 

mass before fusion (kg) = 50

mass after fusion (kg) = 20

Entering these values into the formula or calculator above gives us: 

E = (50-20)*299792458^2 = 2.69 e+18 (Joules)