Half-life Calculator
Solve half-life problems: find the elapsed time, the remaining quantity, or the half-life itself.
Runs 100% in your browser — nothing is uploaded.
Result
Formula
N(t) = N₀ · (½)^(t / t½)
About this calculator
The half-life calculator determines the time required for a quantity to reduce to half its initial value, or computes the remaining amount after a given time, based on exponential decay. The calculator uses the exponential decay model.
How to use
- 1
Select what you want to find: Elapsed time, Remaining amount, or Half-life.
- 2
Enter the known values (Initial amount, and the other two quantities as shown).
- 3
Optionally set the Time unit, then read the result.
Frequently asked questions
What is half-life?
Half-life is the time required for a quantity to reduce to half its initial value. It is commonly used in nuclear physics and chemistry to describe radioactive decay.
How is half-life related to decay constant?
The decay constant (λ) is related to half-life by the equation λ = ln(2)/T½. It represents the probability of decay per unit time.
Can half-life be used for non-radioactive processes?
Yes, half-life applies to any process that follows exponential decay, such as drug elimination from the body or the discharge of a capacitor.
Please note: Results are estimates for general information only and are not professional or medical/financial advice.