Radioactive Decay Remaining
Provide the initial amount, the isotope's half-life, and elapsed time to estimate how much material remains. The calculation assumes simple exponential decay.
Simplified model; consult physics texts for detailed decay behavior.
Examples
- 100 g with 5 y half-life after 5 y ⇒ 50 g remain
- 80 g with 2 y half-life after 6 y ⇒ 10 g remain
- 1 g with 3 d half-life after 9 d ⇒ 0.125 g remain
FAQ
Must time and half-life use the same units?
Yes. Use consistent units to obtain a valid result.
Does the environment affect decay?
Under normal conditions, decay rate is unaffected by external factors.
What if the elapsed time is zero?
The remaining amount equals the initial quantity.
Can this calculator handle decay chains?
No. It assumes a single-step decay process only.
Additional Information
- Half-life is the time required for half of the material to decay.
- This model ignores decay chains and assumes conditions remain constant.
Connect decay inventories with cross-section analysis
After projecting remaining activity, review the barn (b) unit guide to keep reaction probabilities, shielding updates, and activation planning in sync with ISO 80000-10 terminology.