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Find your caffeine cutoff
Estimate when to have your last caffeinated drink and see how much caffeine may still be active when you go to bed.
An educational planning estimate. This is not medical advice and it cannot guarantee how you will sleep.
Suggested last-caffeine window
1:00 PM – 3:00 PM
Based on your 11:00 PM bedtime, what you have entered and your selected sensitivity, this window may leave less caffeine active near bedtime. Your actual response may differ.
- Bedtime
- 11:00 PM
- Total caffeine today
- 96 mg
- Estimated at bedtime
- 32 mg
- Last caffeine to bed
- 8 hours
That is above 400 mg, the figure most often cited as a reference for healthy adults. This tool cannot tell whether that is appropriate for you — it knows nothing about your health, medication or circumstances. If you are curious about it, a healthcare professional is the right person to ask.
- Your last caffeine is 8 hours before bed, which is already outside the suggested window.
A curve showing estimated caffeine declining through the day, with a marker at bedtime. The same figures are listed in the table below.
| Drink | Time | Caffeine | At bedtime |
|---|---|---|---|
| Brewed coffee | 3:00 PM | 96 mg | 32 mg |
Your next step
Your Day Shapes Your Night
Caffeine, evening meals, hydration and alcohol — observing your own patterns without restrictive eating.
Build a more sleep-friendly caffeine routine $19.00Not ready for that? Start with a free sleep guide .
About this calculator
Caffeine leaves the body gradually rather than all at once. This tool estimates how much of what you drink today may still be active at bedtime, and suggests a window for finishing your last caffeinated drink. It is a planning estimate, not medical advice, and it cannot tell you how you personally respond.
Important context
- Individual response to caffeine varies a great deal, and half-life differs from person to person.
- Pregnancy, breastfeeding, medications and health conditions can all change what amount is appropriate.
- If you are pregnant or breastfeeding, speak to a healthcare professional. 200 mg per day is a commonly used reference.
- This calculator is designed for adults.
- Children and teenagers should talk about caffeine with a parent, guardian or healthcare professional.
- Energy drinks are not recommended for children and teenagers.
- Symptoms such as palpitations, tremor or severe anxiety are worth discussing with a healthcare professional.
- If you are cutting down from heavy habitual use, reducing gradually is usually more manageable than stopping abruptly.
How the estimate is calculated
Each drink is treated as a single dose that decays exponentially: half remains after one half-life, a quarter after two, and so on. Remaining caffeine is calculated as dose × 0.5 ^ (hours elapsed ÷ half-life), and the amounts from every drink are added together at your bedtime. The suggested window comes from your total intake and selected sensitivity, then is presented as a two-hour range rather than a single minute, because the underlying evidence does not support that level of precision.
References
- FDA — Spilling the Beans: How Much Caffeine is Too Much?
- Drake et al. (2013), Caffeine Effects on Sleep Taken 0, 3, or 6 Hours Before Going to Bed
- EFSA Scientific Opinion on the Safety of Caffeine (2015)
Last reviewed 2026-08-05.
Common questions
When should I stop drinking coffee before bed?
There is no single correct time. A common starting point is to finish caffeine somewhere between six and twelve hours before bed, depending on how much you have had and how sensitive you are. This tool suggests a window based on those two things, and the most useful next step is to try it for a week and notice what changes.
How long does caffeine stay in your system?
Caffeine has a half-life of roughly five hours in most adults, meaning about half of a dose remains after five hours and about a quarter after ten. The range across individuals is wide — genetics, medication, smoking and pregnancy all affect it — so treat any single number as an estimate.
Does caffeine still affect sleep if I fall asleep fine?
It can. Research has found that caffeine taken even six hours before bed can reduce total sleep time and lighten sleep, in people who did not notice a problem falling asleep. Falling asleep easily is not by itself evidence that caffeine is not affecting your night.
Is decaf caffeine-free?
No. Decaf coffee typically contains a small amount — around 2 mg per cup, compared with roughly 96 mg for regular brewed coffee. For most people that is negligible near bedtime, which is why it is included here as its own preset.
How accurate is this calculator?
It is a planning estimate, not a measurement. It uses average caffeine figures for typical servings and an average half-life for the sensitivity you select. Actual caffeine content varies by brand, preparation and serving size, and your personal metabolism may differ substantially from the model.