Enter the mass before decay (kg) and the mass after decay (kg) into the calculator to determine the Decay Energy.

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## Decay Energy Formula

The following equation is used to calculate the Decay Energy.

**E = (M1-M2) * c^2**

Variables:

- Where E is the Decay Energy (Joules)
- M1 is the mass before decay (kg)
- M2 is the mass after decay (kg)
- c is the speed of light (299792458 m/s)

## How to Calculate Decay Energy?

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

**Example Problem #1:**

- First, determine the mass before decay (kg). In this example, the mass before decay (kg) is measured to be 50.
- Next, determine the mass after decay (kg). For this problem, the mass after decay (kg) is calculated to be 20.
- Finally, calculate the Decay 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 = (50-20) * 299792458^2 = 2.69 e+18 (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 decay (kg) = .000024

mass after decay (kg) = .000012

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

E = (.000024-.000012) * 299792458^2 = 1.0785 e+12** **(Joules)