Half-life is the time it takes for half of a decaying substance to disappear, and it governs radioactive decay, drug clearance and many other exponential processes. This calculator uses the decay law where the remaining amount equals the initial amount multiplied by one half raised to the power of the elapsed time divided by the half-life. Enter an initial quantity, a half-life and an elapsed time to see how much remains, along with the number of half-lives that have passed and the fraction left. Because the decay is exponential, the amount never quite reaches zero but halves again with each half-life period. It is a core idea in nuclear physics, chemistry and pharmacology. Keep the half-life and elapsed time in the same units and the result computes instantly in your browser.
The remaining amount equals the initial amount times one half raised to the number of elapsed half-lives, based on exponential decay.
Yes. Enter an initial amount, a remaining amount, and the elapsed time, and it solves for the half-life.
A half-life is the time it takes for half of a decaying substance to remain, and it stays constant for a given isotope.
Half-life is the time it takes for half of a decaying substance to disappear, and it governs radioactive decay, drug clearance and many other exponential processes. This calculator uses the decay law where the remaining amount equals the initial amount multiplied by one half raised to the power of the elapsed time divided by the half-life.
Yes. Half-Life Calculator is completely free, with no sign-up and no usage limits.
Yes. Half-Life Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Half-Life Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.