Nutrition
Caffeine remaining after a time
Exponential decay by half life, the standard pharmacokinetic model.
The Formula
remaining = dose x 0.5 ^ (hours / half life)
Exponential decay by half life, the standard pharmacokinetic model.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| remaining | Amount left | mg | Caffeine still active, in milligrams. |
| dose | Dose | mg | The amount originally consumed, in milligrams. |
| hours | Elapsed time | hours | Time since the dose, in hours. |
| half life | Half life | hours | About 5 hours in healthy adults. |
What Each Symbol Means
remainingmg
Amount left
Caffeine still active, in milligrams.
dosemg
Dose
The amount originally consumed, in milligrams.
hourshours
Elapsed time
Time since the dose, in hours.
half lifehours
Half life
About 5 hours in healthy adults.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate caffeine half life page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Caffeine Half Life, filed under Health. Every number the guide produces comes from substituting into this one line.