Exponential Half-Life Decay Calculator
Use the same duration unit for elapsed time and half-life.
Your result
MATHEnter your values and select calculate.
On this page How it works & practical examples
How to use the Exponential Half-Life Decay Calculator
Use the same duration unit for elapsed time and half-life. This is a constant exponential decay model of an amount, not a substance-specific lookup.
The calculation
Worked example
100 units after 20 time units with a ten-unit half-life leaves 25 units, or 25% of the initial amount.
Assumptions and limits
No radioactive handling, medication dosing or biological elimination recommendation. Changing conditions, multiple decay pathways and nonlinear clearance are excluded.
Common questions
Which inputs should I use?
Use the same duration unit for elapsed time and half-life. This is a constant exponential decay model of an amount, not a substance-specific lookup.
What does the result exclude?
No radioactive handling, medication dosing or biological elimination recommendation. Changing conditions, multiple decay pathways and nonlinear clearance are excluded.