Coffee Kick Calculator

Your details

Number of servings (cups, cans, or shots).
Use decimal hours: 7.5 = 7:30 AM, 13 = 1:00 PM.
h
h
The current time, used to calculate how much caffeine is in your system right now. Use decimal hours: 14.5 = 2:30 PM.
h
Caffeine half-life varies by genetics, liver function, and medication. Most people clear about half the caffeine in roughly 5 hours.
Enter when you plan to sleep. The calculator will tell you if caffeine will still be above sleep-safe levels at bedtime. Use values above 24 for after midnight: 25 = 1:00 AM.
h
Total caffeine todayWithin safe limit
217mg

Combined caffeine from all drinks entered

Caffeine in your system now128mg
Peak caffeine level142mg
Percent of daily safe limit1%
Hours until sleep-safe13.4h
Sleep-safe time3:22 AM
Caffeine at bedtime42mg
Your caffeine half-life5h
217 mg
Low<200Moderate200-400High400-500Very high500+

Your caffeine looks fine today (217 mg of 400 mg max).

  • Your total caffeine of 217 mg is 54% of the 400 mg daily guideline, leaving you room within the safe limit.
  • Right now you have approximately 128 mg of caffeine in your system. The typical alertness effect of caffeine lasts 4 to 6 hours after peak absorption.
  • Caffeine will drop to sleep-safe levels (below 20 mg) in about 13.4 hours, around 3:22 AM.
  • At bedtime you will have about 42 mg remaining, a low level that is unlikely to cause major disruption for most people.

Next stepYour half-life is 5.0 hours. For the best sleep, stop all caffeine at least 10 hours before bedtime.

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