Radioactivity Calculator

From its half-life $ \lambda $ (in years) and its current measured radiometric 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 radiometric 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 (several hundred or thousand years old) via the calculations above.

For shorter durations (decades), and recent materials, tritium dating is used. Tritium has been present in large numbers on Earth since nuclear tests.