Calculate the remaining amount of a radioactive substance after decay, given the initial quantity, half-life, and elapsed time.
How it works
- Input the initial quantity of the substance.
- Enter the specific half-life of the isotope in your time unit.
- Provide elapsed time to let the tool model exponential radioactive decay remaining.
Frequently asked questions
What is a half-life?
The time it takes for half of a radioactive substance to decay. Each half-life halves the remaining amount — never reaching exactly zero.
How is half-life used in medicine?
Radioactive tracers and treatments are chosen partly by half-life — long enough to be effective, short enough to clear the body safely.
What has a very short half-life?
Francium-223: 22 minutes. Technetium-99m (medical imaging): 6 hours. Carbon-14 (dating): 5,730 years.