Half-Life Calculator

A half-life calculator computes radioactive decay, drug elimination, or any exponential decay process. The half-life is the time for a quantity to reduce to half its starting value

The calculator uses the standard published formula for half-life. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: N(t) = N₀ × (½)^(t/t½). Each step in the calculation is shown so you can verify the result manually.