Radioactive Decay Calculator
Calculate the remaining amount of a radioactive substance after a given time using the half-life decay formula.
Remaining Amount
Radioactive decay follows the exponential decay formula using the half-life:
N(t) = N₀ × (1/2)^(t / t½)
Where:
- N(t) = remaining amount after time t
- N₀ = initial amount
- t½ = half-life (time for half the substance to decay)
- t = elapsed time
Common half-lives:
- Carbon-14: 5,730 years
- Uranium-238: 4.5 billion years
- Iodine-131: 8.02 days
- Cobalt-60: 5.27 years
- Radon-222: 3.82 days
After 1 half-life, 50% remains. After 2 half-lives, 25% remains. After 10 half-lives, less than 0.1% remains.