How to use the decay constant and mean lifetime calculator
Find the decay constant and mean lifetime of a radioactive isotope from its half-life. Enter half-life in the field above; the decay constant, mean lifetime are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “decay constant from half-life”, “mean life”, “lambda = ln 2 over half-life”, “calculate decay constant and mean lifetime”, “find decay constant”.
Formula
Variables
- T — Half-life (years)
Worked example
With half-life = 30 years, the calculator gives decay constant ≈ 0.02310491 per year; mean lifetime ≈ 43.28085 years.
Frequently asked questions
What is the decay constant and mean lifetime calculator used for?
Find the decay constant and mean lifetime of a radioactive isotope from its half-life. It helps with questions such as “decay constant from half-life”, “mean life”, “lambda = ln 2 over half-life”.
What is the formula for the decay constant and mean lifetime calculation?
Decay constant (per year) = ln(2) / T. Mean lifetime (years) = 1 / [Decay constant]. Here T is half-life (years).
What inputs do I need for the decay constant and mean lifetime calculator?
You need half-life in years. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the decay constant and mean lifetime calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the decay constant and mean lifetime result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.