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Caffeine cutoff calculator

Find the last time to have coffee, tea, or an energy drink for your bedtime, and see how much caffeine is likely still in your system when you lie down. No signup needed.

I wake up at

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I try to go to sleep at

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What are you drinking?

Servings

Caffeine clears slower for me

Clearance can be slower with pregnancy, oral contraceptives, some medications, liver conditions, or just naturally. This switches the chart and table to a half-life of about 9 hours instead of 5. It is not medical advice.

Your caffeine cutoffEstimate only, based on typical values.

Wake 6:30 AM · Lights out 10:30 PM. Drawn around your routine, not local sunrise or sunset.

2:30 PM

Last caffeine

That is 8 hours before your 10:30 PM bedtime, the same buffer your Calibrate plan uses. With your drink and a 5-hour half-life, about 59 mg would still be around at bedtime.

How much is still in your system

Estimated caffeine remaining until bedtimeDrink at 12:30 PM: about 45 mg left at bedtime. Drink at 2:30 PM: about 59 mg left at bedtime. Drink at 4:30 PM: about 78 mg left at bedtime.0100200mg12 PM2 PM4 PM6 PM8 PM10 PMBedtime 10:30 PM12:30 PM45 mg2:30 PM59 mg4:30 PM78 mg

If you have 180 mg at a given time, about this much is still around at bedtime.

  1. 112:30 PM, 10 h before bedAbout 45 mg left83 mg with a 9 h half-life
  2. 22:30 PM, 8 h before bedAbout 59 mg left97 mg with a 9 h half-lifeYour cutoff
  3. 34:30 PM, 6 h before bedAbout 78 mg left113 mg with a 9 h half-life

Your cutoff is one part of your day

Caffeine timing works best alongside when you get light, when you wind down, and when you wake. Answer a few questions and Calibrate builds a daily plan around your real schedule.

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Related reads: How to fix your sleep schedule with light timing and How much morning sunlight you need.

Caffeine half-life calculator: how the estimate works

Typical half-life

About 5 hours for many healthy adults

Calibrate cutoff

8 hours before bed

Still measured less sleep

Caffeine 6 hours before bed 1

Learn more

Caffeine does not switch off when you stop feeling it. Your body clears it gradually, and the time it takes to clear half is called the half-life. For many healthy adults that is around 5 hours, so a drink with 180 mg of caffeine leaves about 90 mg after 5 hours and about 45 mg after 10.

The calculator takes the typical caffeine in your drink, multiplies it by your servings, and halves it every 5 hours (or every 9 hours if you choose slower clearance). The chart plots what is left from the moment you drink until bedtime. Your headline cutoff is eight hours before bed, the same rule Calibrate uses when it builds a personal plan, which is more cautious than the 6-hour mark where one controlled study still measured less sleep1,2.

Why this is an estimate

Half-life differs a lot between people. Genetics, smoking, pregnancy, oral contraceptives, some medications, and liver conditions all change how fast caffeine is cleared 3. Drink sizes vary too: a 12 oz brewed coffee can contain anywhere from roughly 110 to 250 mg depending on the beans and brew 4. The amounts in the drink list are typical figures, and you can enter your own with the custom option.

Learn more

Sensitivity is a separate question from clearance. Two people with the same caffeine level at bedtime can sleep differently. Treat the result as a starting point, then notice how you sleep over a week or two and adjust.

What about waiting 90 minutes after waking?

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Some people wait about 90 minutes after waking before their first coffee. The idea is popular, but direct evidence in people is mixed, so it is something to test, not a rule. The calculator does not depend on it. What has more support is the other end of the day: caffeine taken in the 6 hours before bed is associated with less sleep 1,2.

Caffeine cutoff FAQ

When should I stop drinking coffee?

A common rule of thumb is to stop at least 6 to 8 hours before bed. Calibrate uses 8 hours: if you go to bed at 10:30 PM, your last coffee is by 2:30 PM. One controlled study found that caffeine taken 6 hours before bedtime still reduced sleep time, so earlier can help if you are sensitive.

How late can you drink coffee and still sleep?

It depends on how fast your body clears caffeine, how much you drink, and how easily you fall asleep. Many people can have a small cup in the early afternoon without trouble, while others notice effects from a morning cup. The chart above shows roughly how much is left at bedtime for different drink times, so you can see the trade-off and test what works for you.

What is the half-life of caffeine?

Half-life is the time it takes for your body to clear half of the caffeine in your blood. For many healthy adults it is around 5 hours, so a 200 mg dose has fallen to about 100 mg after 5 hours and about 50 mg after 10. It varies a lot from person to person, and it can be longer with pregnancy, oral contraceptives, some medications, and liver conditions.

Does caffeine affect sleep even if I fall asleep fine?

It can. Research on caffeine and sleep, including a 2023 systematic review, links caffeine taken in the hours before bed with shorter total sleep time and lower sleep efficiency, even when people feel they fell asleep without trouble. How much this matters differs between people.

Is it better to wait 90 minutes after waking for coffee?

Some people delay their first coffee by about 90 minutes, on the idea that it avoids a mid-morning crash. The evidence for this in humans is mixed, so treat it as something you can test rather than a rule. Your last-caffeine time at the end of the day is better supported than the timing of the first cup.

How accurate is this caffeine cutoff calculator?

It is an estimate. It uses typical caffeine amounts for each drink and a simple half-life model, and it cannot account for your genetics, medications, body size, or how much food is in your stomach. It is wellness education, not medical advice. If you are pregnant or have a medical condition, ask your health care provider about your caffeine limits.

References

  1. Drake C, Roehrs T, Shambroom J, Roth T (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11), 1195-1200. doi.org/10.5664/jcsm.3170
  2. Gardiner C, Weakley J, Burke LM, et al. (2023). The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews, 69, 101764. doi.org/10.1016/j.smrv.2023.101764
  3. Grzegorzewski J, Bartsch F, Koller A, Konig M (2022). Pharmacokinetics of caffeine: a systematic analysis of reported data for application in metabolic phenotyping and liver function testing. Frontiers in Pharmacology, 12, 752826. doi.org/10.3389/fphar.2021.752826
  4. US Food and Drug Administration (2024). Spilling the beans: how much caffeine is too much?. FDA Consumer Update. www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much

This calculator is for wellness education and gives estimates, not medical advice. It does not diagnose or treat any condition. If you are pregnant, take medication, or have a health condition, talk with your health care provider about caffeine.

Caffeine Cutoff Calculator: When to Stop Coffee | Calibrate