How to use the radioactivity activity calculator
Find activity of a radioactive sample from atoms and half-life. Enter number of nuclei, half-life in the fields above; the activity, activity are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- N — Number of nuclei
- th — Half-life (s)
Worked example
With number of nuclei = 1e15, half-life = 3600 s, the calculator gives activity ≈ 1.9254 × 10¹¹ Bq; activity ≈ 5,203,808 µCi.
Frequently asked questions
What is the formula for the radioactivity activity calculation?
Activity (Bq) = ln(2) / th × N. Activity (µCi) = [Activity] / 3.7e4. Here N is number of nuclei, th is half-life (s).
What inputs do I need for the radioactivity activity calculator?
You need number of nuclei, half-life in s. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.