Caffeine Clearance Calculator
Wondering why that evening coffee keeps you awake? Enter how much caffeine you had and when bedtime is, to see exactly how much is still active in your body hour by hour — based on the 5-hour half-life.
Enter your details above and the result will appear here.
How to use
- Enter the caffeine amount in milligrams.
- Enter how many hours pass between the drink and bedtime.
- See what remains each hour and at bedtime.
Note
Uses exponential decay with a 5-hour half-life: remaining = amount x 0.5^(hours/5). Half-life varies between people (roughly 3 to 7 hours) and is longer in pregnancy and with some medicines. Estimate only — not medical advice.