Radioactive Decay Calculator

Calculate isotope activity over time using radioactive decay formulas

Calculate current activity from original activity, or reverse calculate to find original activity from current measurements.

Select Element

Select Isotope

Isotope Not Listed? (Enter Manually)

Isotope Name

Half-Life Value

Half-Life Unit

Original Activity

Original Unit

Original Date/Time

Calculation Date/Time

Calculate Activity In

Isotope:

Half-Life:

Time Elapsed:

Number of Half-Lives:

Original Activity:

Calculated Activity:

Percent Remaining: