Enter the half-life into the calculator to determine the decay constant, also known as the decay rate.

Decay Constant Formula

The following formula is used to calculate the decay constant.

λ = ln (2) / t(1/2) 
  • Where λ is the decay constant (s^-1)
  • Where t1/2 is the half-life (seconds)

To calculate the decay constant, divide the natural log of 2 by the half-life.

Decay Constant Definitin

A decay constant is defined as the ratio between the half-life of a number and the total size of the number.

Decay Constant Example

How to calculate decay constant?

  1. First, determine the half life.

    The half-life is the total time it takes for the population or amount to diminish to 1/2 its original size.

  2. Next, calculate the decay constant.

    Using the formula above, plug in the half life.


What is a decay constant?

A decay constant is the proportionality between the total size of a number and the rate of decay. This is most often used in physics when analyzing elements that undergo radioactive decay.