Decay energy

Decay energy is the net release of energy in an exothermic fission reaction. Put another way, it is the amount of energy that must be added to fuse two nuclei in an endothermic fusion reaction.

Decay calculation
A useful measure of the energy decay is denoted by Q, the kinetic energy liberated in the decay of the particle at rest.

Q = (Kinetic energy)after - (Kinetic energy)before

or

Q = ((Rest mass) x c2)before - ((Rest mass) x c2)after