Overview
What Is a Half-Life Calculator?
This tool calculates how much of a radioactive substance remains after a given time period, based on its half-life.
Calculate radioactive decay over time.
This tool calculates how much of a radioactive substance remains after a given time period, based on its half-life.
Useful for coursework involving radioactive decay and nuclear chemistry.
Input the starting quantity.
Input the substance's half-life period.
Input how much time has passed.
The result updates automatically.
Remaining Amount = Initial Amount × (1/2)^(elapsed time ÷ half-life)
The time required for half of a radioactive substance to decay into a different form.
No, half-life is a constant property of the specific radioactive isotope, regardless of how much remains.
Ensure elapsed time and half-life use the same time unit (both years, both days, etc.) for accurate results.
No, calculations happen entirely in your browser.
Radiometric dating, nuclear medicine, radioactive waste management, and pharmacology (drug half-life) all use similar decay math.
Mathematically, it approaches but never reaches exactly zero - it decreases asymptotically.
The mathematical principle is the same exponential decay pattern, though applied to different substances.
Yes, the same fundamental half-life math underlies carbon dating and other radiometric dating methods.
Yes, completely free with no sign-up required.