Radioactive Decay Calculator
How much material remains after this number of half-life intervals? Enter the stated values to calculate this model.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Initial amount (amount) | Enter initial amount in amount; use the same basis as the other measurements. |
| Elapsed time (time) | Enter elapsed time in time; use the same basis as the other measurements. |
| Half-life (time) | Enter half-life in time; use the same basis as the other measurements. |
Understanding your result
Read Remaining amount (amount), Decayed amount (amount) in the units and model stated on this page. The formula remaining=initial*2^(-time/halfLife) · decayed=initial-remaining defines the relationship; measurement accuracy and model applicability are separate from numerical precision.
Common mistakes
- Mixing input units or changing the physical meaning of a variable without changing the model.
Check your calculation
- Use the worked example as a known reference case, then change one input at a time and check the direction and units of the response.
Calculation checks, sources and review limits
How much material remains after this number of half-life intervals?
How much material remains after this number of half-life intervals? Enter the stated values to calculate this model.
Common uses
- How much material remains after this number of half-life intervals
How it works
remaining=initial*2^(-time/halfLife); decayed=initial-remaining
Worked example
Enter Initial amount: 100 amount; Elapsed time: 10 time; Half-life: 5 time. Results: Remaining amount: 25 amount; Decayed amount: 75 amount.