Half Life Calculator






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Introduction to the Half-Life Calculator

The half-life of any radioactive element can be calculated by applying the half-life calculator. The conventional method of calculating the half-life of an element is by using the half-life formula. But today, these chemistry problems have become much easier to solve by using a half-life calculator. The half-life of a radioactive element is calculated to estimate the age of the element. Read on further to learn about the concept of half-life and the benefits of the half-life calculator.

Definition of the Half-Life

The radioactive elements contain unstable nuclei which continuously emit energy in the form of rays. This continuous emission of energy is called radioactive decay. The amount of time in which half of the radioactive element decays is called its half-life. The half-life value of a certain element is always constant. It is independent of environmental conditions and the initial amount of the element. The concept of half-life is also applied to chemical reactions. In a chemical reaction, half-life is the time in which half of the reactants are converted to products.

How to use the Half-Life Calculator?

  • Enter the initial amount of the radioactive substance.
  • Calculate and enter the remaining amount of the radioactive substance after time t.
  • Enter the time taken by the substance for its decay.
  • Press the “calculate” button to get the value of the half-life of the substance.

Now, let us take an example to calculate the half-life of a substance using the half-life calculator. Suppose, we take a substance A.

  • The initial amount(Nt) of A is 10g.
  • Determine the remaining amount(N0) of A after 5min. e.g., N0 = 4g.
  • The time taken by A to decay from 10g to 4g is 5min. so, t = 5min.
  • Now, enter the values in the calculator and find the half-life of the substance which in this case is 3.7.
  • The half-life of substance A in our experiment is t1/2 = 3.7.

Formula to Calculate Half-Life

As we know that half-life of an element is the time required to reduce the amount of the element to half of its original value. The half-life is calculated by calculating the remaining amount of the element after time t. half-life is denoted by t1/2. The formula is given as

N(t) = N0 x (0.5)t / t1 / 2


N(t) is the amount of the substance after time t, N0 is the initial amount of substance, t is the time elapsed, and t1/2is the half-life of the substance. t / t1/2 is also denoted by n and it is the number of half-lives. So, the above formula can be written as

N(t) = N0 x (0.5)n

There are some other parameters available to calculate the half-life of a substance. is the mean lifetime of the substance and ƛ is the decay constant. The value of the decay constant is different for different substances. Another formula to calculate the half-life can be written as

T1/2 = ln (2) / ƛ = ln (2)

The value of ln (2) is 0.693. it is the natural logarithm of 2.

The half-life of a chemical reaction is also determined by using the reaction orders. The formula is

T1/2 = [A] 0 / 2k


[A] 0 is the initial amount of reactant, and is the rate constant.

Example for calculation

Suppose the decay constant of a substance is 0.96s-1. Then calculate the half-life of the substance.

Apply the formula as

t1/2 = ln (2) / ƛ
t 1/2 = 0.693/0.96
t 1/2 = 0.7s

The half-life of the above substance is 0.7s.

The calculation of half-life is a complicated task and many of us find it very difficult also. So, the half-life calculator is here to help you with your half-life calculations.


The half-life of a substance is calculated to determine the age of the radioactive specie. The half-life is calculated by comparing the initial amount and the amount of the substance after time t.

There are many parameters for the calculation of half-life and the calculation is also complicated. The half-life calculator helps you calculate the half-life of a substance by entering the values of N(t), N0, and t in the respective icons. The half-life calculator is accurate and easy to use. I hope you get the best experience with this tool.


What is the half-life?

The formula of the half-life.

Example to calculate the half-life.

Alan Walker

Shaun Murphy

Last Updated March 28, 2022

A professional content writer who likes to write on science, technology and education.