Calculate the remaining quantity of a substance after a given time, based on its half-life, using exponential decay.
Half-life and elapsed time must use the same time unit.
This tool calculates how much of a substance remains after a certain time, based on its half-life, the time it takes for half of a quantity to decay.
Remaining quantity N equals initial quantity N0 times one half raised to the power of elapsed time divided by half-life.
Enter the initial quantity, the half-life duration, and the elapsed time using the same time units, then click Calculate.
Example: Carbon-14 has a half-life of 5730 years. Starting with 100 grams, after 11460 years, approximately 25 grams remain.
What is the decay constant. It is calculated as the natural log of 2 divided by the half-life, representing the rate of decay.
Is this only for radioactive decay. No, the same formula applies to any exponential decay process, including drug elimination and certain chemical reactions.