Half-Life Calculator
Half-life of any exponential decay.
Amortization schedule
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Showing first 12 of months.
Growth over time
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Introduction
Half-Life Calculator — Half-life of any exponential decay. Enter Initial amount N₀, Remaining amount Nₜ, Elapsed time to get an instant, accurate result.
Formula
t½ = t × ln(2) / ln(N₀/Nₜ), derived from the exponential decay equation.
Step-by-step
- Enter the Initial amount N₀.
- Enter the Remaining amount Nₜ.
- Enter the Elapsed time.
- Click Calculate to see your result instantly.
Real-world example
Example: With Initial amount N₀ = 100, Remaining amount Nₜ = 25, Elapsed time = 10, the Half-Life Calculator gives Half Life: 5.
Frequently Asked Questions
What does half-life mean?
The time it takes for a quantity to reduce to half its original amount, common in radioactive decay and pharmacokinetics.
Does half-life depend on the starting amount?
No — half-life is constant for a given substance regardless of the starting quantity.
What inputs does the Half-Life Calculator need?
You'll need to provide: Initial amount N₀, Remaining amount Nₜ, Elapsed time. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Half-Life Calculator?
The Half-Life Calculator applies the formula exactly as calculated — t½ = t × ln(2) / ln(N₀/Nₜ), derived from the exponential decay equation. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Half-Life Calculator free to use?
Yes, the Half-Life Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Half-Life Calculator
The Half-Life Calculator uses a real, verifiable formula — t½ = t × ln(2) / ln(N₀/Nₜ), derived from the exponential decay equation. — so results are accurate every time, not an approximation.