Half-Life Decay Simulator
Model radioactive or exponential decay: see how much of a substance remains after a given time.
The exponential decay behind the formula
Radioactive and other exponential decay follows N(t) = N₀ × (1/2)t / half-life — each half-life period reduces the remaining quantity by exactly half, regardless of how much was there to begin with.
A common misreading of "half-life"
A substance with a 10-year half-life isn't "gone" after 20 years — it's down to a quarter of the original amount, and mathematically it never reaches exactly zero, just an increasingly small remaining fraction.