Radioactivity Calculator

From its half-life $ \lambda $ (in years) and its current measured activity $ a $ (in percent), the age $ t $ of the radioactive material is calculated according to the formula:

$$ t = \frac{\lambda}{\ln(2)}\ln\frac{100}{a} $$

Example: $ a = 25\% $, $ \lambda = 1000 $ so $ t = 2000 $ years

From its age $ t $ (in years) and its current measured activity $ a $ (in percent), the half-life of a radioactive material $ \lambda $ (in years) is calculated with the formula :

$$ \lambda = \frac{t \ln(2)}{\ln\frac{100}{a}} $$

From its age $ t $ (in years), and its half-life $ \lambda $ (in years), the activity of a radioactive material $ a $ (in percent) is calculated by the formula:

$$ a = \frac{100}{\exp(\frac{t \ln(2)}{\lambda})} $$

The radioactive period is the time necessary for half of the atoms of a radioactive isotope to decay naturally. The term half-life is a synonym for radioactive period.

Radiometric dating is the technique using a radioactive isotope present in a material (generally Carbon in carbon 14 dating) to determine the age of a material via the calculations above.