How long does caffeine last in your body?
Caffeine peaks within about an hour and then clears gradually. Here is what that looks like for common doses, including how long 75 mg of caffeine lasts.
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The short answer
With the commonly quoted average half-life of about 5 hours, roughly half of a dose is still in your body after 5 hours and about a quarter after 10. How long you feel caffeine can differ from how long it stays in your body, and both vary from person to person.
Estimated caffeine left after one drink
| Dose | 1 h | 3 h | 5 h | 10 h | 15 h |
|---|---|---|---|---|---|
| 50 mg | 44 | 34 | 26 | 13 | 6 |
| 75 mg | 66 | 51 | 39 | 19 | 10 |
| 100 mg | 88 | 68 | 52 | 26 | 13 |
| 200 mg | 177 | 137 | 103 | 52 | 26 |
Single drink, 5-hour half-life, same absorption model as the calculator. Estimates, not measurements.
How long does 75 mg of caffeine last?
A 75 mg drink peaks at about 67 mg roughly 50 minutes after you drink it. It falls below 10 mg after about 9 hours with a fast 3-hour half-life, about 15 hours with a 5-hour half-life, and about 24 hours with a slow 8-hour half-life. These figures describe the amount in your body, not how alert you will feel.
| Time after drinking | Estimated caffeine left (mg) |
|---|---|
| 1 hour | 66 (near the peak) |
| 3 hours | 51 |
| 5 hours | 39 |
| 8 hours | 26 |
| 10 hours | 19 |
| 12 hours | 15 |
| 15 hours | 10 |
| 20 hours | 5 |
What changes the answer
- Your personal half-life: see what changes how fast you clear caffeine.
- Several drinks in a day add together, so earlier coffee still counts.
- Tolerance and sensitivity change how strongly you feel a given amount.
New to the term? Read what the half-life of caffeine means. Not sure how much a drink contains? See caffeine in common drinks.
Want your own numbers?
Open the caffeine half-life calculatorEstimates only, not medical advice. See the disclaimer.