Half-Life Calculator

Solve remaining amount, elapsed time, or half-life using the standard first-order half-life relationship.

Solve for

Initial amount N0

Remaining N

Elapsed time / half-life

—N = N0 × (1/2)^(t / t½)

How to use this Half-Life Calculator

Calculate exponential decay from half-life, elapsed time, and initial amount. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.