How long does caffeine stay in your body?
Caffeine doesn’t vanish when you finish your cup; it is cleared slowly over hours. The simplest way to describe that is its half-life: the time it takes for the caffeine in your body to halve.
What half-life means
With a 5-hour half-life, a mug of filter coffee (≈ 110 mg) at noon is estimated to fade like this:
| Time | Left (estimate) |
|---|---|
| 12:00 | 110 mg |
| 17:00 | 55 mg |
| 22:00 | ≈ 28 mg |
| 03:00 | ≈ 14 mg |
It halves every 5 hours; it never quite reaches zero, it just gets smaller. Several drinks in a day add up on top of each other.
Is it the same for everyone?
No. EFSA gives an adult half-life of roughly 2 to 8 hours. The same noon mug at 11 PM can look like this:
| Clearing pace | Half-life | Left at 11 PM (estimate) |
|---|---|---|
| Fast | ≈ 3 hours | ≈ 9 mg |
| Average | ≈ 5 hours | ≈ 24 mg |
| Slow | ≈ 8 hours | ≈ 42 mg |
What changes the pace is covered in What changes how fast you clear caffeine.
How Caffeine Tracker works it out
Caffeine Tracker counts each drink in full from the time you had it, then halves it at the pace you pick (Fast ≈ 3, Average ≈ 5, Slow ≈ 8 hours). In reality caffeine reaches the blood over about an hour; the app simplifies that and shows the result as an estimate.
Sources: EFSA – caffeine opinion (slides) · Frontiers in Pharmacology 2021 – caffeine pharmacokinetics review
See what's still in you now →General information with sources, not medical advice.