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Caffeine half-life and cutoff calculator

Short answer

A 2023 meta-analysis found that to avoid losing sleep, a regular coffee (about 107 mg) should be finished at least 8.8 hours before bed, and a typical pre-workout serve (217.5 mg) at least 13.2 hours before. For an 11 PM bedtime, that means coffee by about 2:12 PM. Caffeine's half-life varies from about 2 to 10 hours between people.

Last reviewed 12 October 20264 published sourcesNot medical advice

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Caffeine at bedtime

Add each drink with its caffeine in mg and the time you finished it. Labels and cafe menus list caffeine content.

Caffeine half-life

Half-life ranges from about 2 to 10 hours between people. 5 hours is a middle-of-the-range starting point, not your measured value.

  • mg
  • mg

Caffeine today

214 mg

FDA cites 400 mg/day for most adults

Still active at 11:00 PM

≈ 46 mg

with a 5-hour half-life

Coffee cutoff

2:12 PM

8.8 h before bed

With a 11:00 PM bedtime, Gardiner et al.'s meta-analysis suggests finishing a regular coffee by 2:12 PM and a pre-workout serve by 9:48 AM.

  • 107 mg finished 15.0 h before bed → about 13 mg left at bedtime
  • 107 mg finished 8.5 h before bed → about 33 mg left at bedtime

When to stop drinking coffee, by bedtime

A 2023 systematic review and meta-analysis of 24 studies found caffeine cut total sleep time by 45 minutes and sleep efficiency by 7% on average. To avoid losing sleep, it recommended finishing a standard coffee (107 mg per 250 mL) at least 8.8 hours before bed and a typical pre-workout serve (217.5 mg) at least 13.2 hours before (Gardiner et al., 2023).

Latest time to finish caffeine for common bedtimes
BedtimeCoffee (107 mg per 250 mL)Pre-workout (217.5 mg serve)
9:30 PM12:42 PM8:18 AM
10:00 PM1:12 PM8:48 AM
10:30 PM1:42 PM9:18 AM
11:00 PM2:12 PM9:48 AM
11:30 PM2:42 PM10:18 AM
12:00 AM3:12 PM10:48 AM
Calculated from the 8.8 h and 13.2 h minimum gaps in Gardiner et al., Sleep Medicine Reviews 2023.

Caffeine half-life: why the estimate is a range

Your body clears caffeine at its own pace. Its half-life (the time to clear half of it) ranges from about 2 to 10 hours, depending on internal and external factors; nicotine use, for example, can speed caffeine metabolism by as much as 50% (O'Callaghan et al., 2018). With a 5-hour half-life, a quarter of a morning coffee is still in your system 10 hours later. The calculator uses simple halving for each half-life, so pick the setting that best matches how caffeine affects you.

Even 6 hours may not be enough for a big dose

In a home sleep study, 400 mg of caffeine taken at bedtime, 3 hours before or 6 hours before all disrupted sleep compared with a placebo (Drake et al., 2013). 400 mg is also the daily amount the U.S. FDA cites for most adults, which it describes as about two to three 12-ounce cups of coffee (U.S. FDA). Sensitivity varies widely.

Short on sleep already? Work out your weekly total with the sleep debt calculator.

A caffeine cutoff that follows your day

Log a coffee from the Reps widget and Reps shows how much caffeine is still active and the latest time you can have more before it cuts into tonight's sleep.

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Common questions

How long before bed should I stop drinking coffee?

Gardiner et al.'s 2023 meta-analysis of 24 studies recommends finishing a standard coffee (107 mg per 250 mL) at least 8.8 hours before bedtime, and a typical pre-workout serve (217.5 mg) at least 13.2 hours before, to avoid reducing total sleep time.

What is the half-life of caffeine?

Caffeine's half-life varies widely, from about 2 to 10 hours, depending on genetics, smoking, pregnancy, some medications and other factors. With a 5-hour half-life, a quarter of a dose is still circulating 10 hours later.

How much caffeine per day is safe?

The U.S. FDA cites 400 mg a day for most adults as an amount not generally associated with negative effects. Sensitivity varies, and pregnant people and those with some health conditions or medications are often advised to have less.

Sources

Figures on this page were checked against these publications on 12 October 2026.

  1. Gardiner C, Weakley J, Burke LM, Roach GD, Sargent C, Maniar N, et al. The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews. 2023;69:101764. doi.org/10.1016/j.smrv.2023.101764
  2. Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. 2013;9(11):1195–1200. doi.org/10.5664/jcsm.3170
  3. O'Callaghan F, Muurlink O, Reid N. Effects of caffeine on sleep quality and daytime functioning. Risk Management and Healthcare Policy. 2018;11:263–271. doi.org/10.2147/RMHP.S156404
  4. U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine is Too Much? Consumer Update (content current as of 28 August 2024). www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much

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