When should you stop drinking coffee?
Find a caffeine planning time and estimate what may remain at bedtime.
Sleep time
Add drinks
Add each drink and the time you had it. The graph updates from these drinks. Each drink is modelled on its own, with the full amount treated as present at the minute you choose.
Drinks in this estimate
The example drink appears here after the page finishes loading.
An ordinary same-day estimate does not need dates. Change them here when a drink was on another day, or when daylight saving makes a time skipped or repeated.
The default is 5 hours. The planning time uses two half-lives and does not move when the drink size changes.
Caffeine over time
Example
Illustrative coffee cutoff: 1:00 PM Estimated caffeine remaining at bedtime: 18.4 milligrams.
10 hours before bedtime using the default two-half-life planning model.
Estimated caffeine remaining at bedtime: 18.4 mg
Educational estimate, not a guaranteed safe cutoff or sleep-quality prediction.
This is an educational planning model, not a medical diagnosis or a measurement of caffeine in your blood. It cannot tell you how you will sleep.
The planning time is two half-lives before bedtime. At the default 5-hour half-life, that is 10 hours. The drink size does not move that time. The bedtime figure adds every drink from the minute you enter. This is not a blood test.
Research reference
Research example, kept separate from the planning time: in one study of healthy adults, 400 mg of caffeine taken 0, 3, or 6 hours before bed reduced total sleep time even at 6 hours (Drake et al., Journal of Clinical Sleep Medicine 2013;9(11):1195-1200). That study is not a personal cutoff and not a leftover-caffeine target.