If you go to bed at 10:00 pm, your last coffee should be at 4:00 pm — or at 2:00 pm if you are sensitive to caffeine. That is the short answer this calculator gives you, tailored to your own bedtime. Caffeine does not simply wear off when you stop feeling alert; it lingers in your system for hours, quietly making it harder to fall asleep and reducing the deep sleep you get even when you do drift off. Enter your usual bedtime below, tell us whether you are a standard or sensitive sleeper, and optionally add the caffeine in your last drink to see roughly how much would still be in your system at bedtime. If sleep timing is the wider problem, our sleep calculator can plan your bedtime around your wake-up call.
A standard sleeper stops caffeine 6 hours before bedtime; a sensitive sleeper — someone who notices even a small coffee late in the day — stops 8 hours before. So a 10:00 pm bedtime means a 4:00 pm cutoff for most people and a 2:00 pm cutoff for sensitive sleepers. Use the calculator below for your exact bedtime.
The cutoff is simple subtraction, and that simplicity is the point: it is a planning rule you can actually follow, not a laboratory measurement of your personal metabolism. For a standard sleeper, the recommended last-caffeine time is your bedtime minus 6 hours. For a sensitive sleeper, it is your bedtime minus 8 hours. A 10:00 pm bedtime therefore gives 4:00 pm for a standard sleeper and 2:00 pm for a sensitive sleeper, while an 11:30 pm bedtime gives 5:30 pm for a standard sleeper and 3:30 pm for a sensitive sleeper. If your bedtime is very early — say 9:00 pm — the standard cutoff is 3:00 pm, which is why many early risers find that an after-lunch coffee is their last one of the day.
| Usual bedtime | Standard cutoff (bedtime − 6 hours) | Sensitive cutoff (bedtime − 8 hours) |
|---|---|---|
| 9:00 pm | 3:00 pm | 1:00 pm |
| 9:30 pm | 3:30 pm | 1:30 pm |
| 10:00 pm | 4:00 pm | 2:00 pm |
| 10:30 pm | 4:30 pm | 2:30 pm |
| 11:00 pm | 5:00 pm | 3:00 pm |
| 11:30 pm | 5:30 pm | 3:30 pm |
| Midnight | 6:00 pm | 4:00 pm |
| 12:30 am | 6:30 pm | 4:30 pm |
Why 6 and 8 hours, rather than "whenever you stop feeling wired"? Because caffeine's half-life — the time it takes your body to clear half of it — is roughly 5 to 6 hours in most healthy adults. That means the alert feeling fades long before the caffeine is gone. A 200 mg coffee at noon leaves about 100 mg in your system around 5:00–6:00 pm, and about 50 mg around 11:00 pm. Even a drink taken at the standard cutoff still leaves a meaningful amount behind at bedtime: after 6 hours, roughly half of it remains. The cutoff does not promise zero caffeine at bedtime; it keeps the remaining amount low enough, and the timing early enough, that most people fall asleep without much trouble. Sensitive sleepers get the extra two hours because their sleep is disturbed by smaller remaining amounts.
Half-life is easier to grasp with a concrete example. Imagine a 200 mg coffee — roughly a large brewed coffee — drunk at noon. Using a midpoint half-life of 5.5 hours, the amount remaining falls like this: about 200 mg at noon, about 100 mg at roughly 5:30 pm, about 50 mg at roughly 11:00 pm, and about 25 mg at roughly 4:30 am. That is why an afternoon coffee can still be echoing through your night even if you felt fine by dinner. The same arithmetic applies to smaller drinks, just scaled down: a 95 mg brewed coffee at noon leaves about 48 mg at 5:30 pm and about 24 mg at 11:00 pm. And the reverse is also true — a coffee drunk at your cutoff time still leaves about half its caffeine at bedtime for a standard sleeper, which is why the sensitive cutoff exists and why, if your sleep is fragile, an even earlier personal cutoff is a reasonable experiment.
Half-life varies from person to person. It is longer in pregnancy, with some medications, and with liver conditions, and shorter in smokers and in some people for genetic reasons. Older adults also tend to clear caffeine more slowly. The calculator uses the typical 5–6 hour range and a 5.5-hour midpoint for its illustration only; your own clearance could be faster or slower, so treat the decay estimate as a rough guide and your own sleep as the final judge. If you consistently sleep badly despite respecting the cutoff, the honest next step is an earlier cutoff or a lower daily total — not a stronger sleep aid to fight the caffeine.
Example 1 — 10:00 pm bedtime, standard sensitivity. Cutoff = 10:00 pm minus 6 hours = 4:00 pm. A 200 mg coffee at 4:00 pm leaves, after 6 hours at a 5.5-hour half-life, about 200 × 0.5^(6 ÷ 5.5) = about 94 mg at bedtime. That sounds like a lot, but it is less than half the starting dose and, for most people, low enough to fall asleep normally — the cutoff is a compromise between enjoying caffeine and protecting sleep, not a guarantee of zero caffeine.
Example 2 — 10:00 pm bedtime, sensitive. Cutoff = 10:00 pm minus 8 hours = 2:00 pm. The same 200 mg coffee at 2:00 pm leaves about 200 × 0.5^(8 ÷ 5.5) = about 73 mg at bedtime. The extra two hours buy a meaningful reduction, which is exactly what sensitive sleepers need.
Example 3 — 11:30 pm bedtime, standard sensitivity. Cutoff = 11:30 pm minus 6 hours = 5:30 pm. A 95 mg brewed coffee at 5:30 pm leaves about 95 × 0.5^(6 ÷ 5.5) = about 45 mg at bedtime. A late bedtime is forgiving: the same rules give a later cutoff, which is one genuine perk of being a night owl.
The U.S. Food and Drug Administration (FDA) states that 400 mg of caffeine per day is an amount that is generally not associated with dangerous, negative effects in healthy adults — roughly the amount in four 8 fl oz (237 ml) cups of brewed coffee, though coffee-shop servings vary widely and can be much stronger. That daily figure is separate from timing: 400 mg drunk entirely before noon is a very different night from 400 mg spread through the evening, and the cutoff rule still applies on top of the daily total. Pregnant people, children and adolescents, and people with certain heart conditions or anxiety disorders are advised to be more cautious, and the FDA notes that individual sensitivity varies — another reason the sensitive cutoff exists. Energy drinks, pre-workout powders, and some pain relievers add caffeine that is easy to miss, so count those in your daily total as well as coffee and tea.
Treat the cutoff as a daily boundary, not a punishment. Move your last coffee earlier in stages if needed — from 6:00 pm to 4:00 pm over a few days is easier than quitting cold turkey at noon — and replace the late drink with something that keeps the ritual without the stimulant: decaf coffee, herbal tea, or sparkling water. Watch the hidden sources too: a chocolate dessert, a cola with dinner, or a pre-workout scoop at 6:00 pm can quietly break a cutoff you kept all day with coffee. If you use caffeine to survive a sleep debt, that is a signal to fix the sleep, not to add more caffeine — our sleep debt calculator can show how far behind you are. And if you follow the cutoff for two weeks and still struggle to fall asleep, talk to your doctor: persistent insomnia has many causes, and caffeine is only one of them.
Written by the Live Fitness Check editorial team · Reviewed against our calculator methodology · Last updated November 2026
Disclaimer: This calculator is for educational purposes only and is not medical advice. Caffeine cutoff times are conservative planning guidance based on a typical 5–6 hour half-life, not a measurement of your personal metabolism. If you are pregnant, take medication, or have a heart condition, anxiety disorder, or persistent sleep problems, talk to your doctor about your caffeine intake.
