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Caffeine Half-Life Calculator

Find out how much caffeine is still in your system at bedtime.

Initial dose

95 mg

Still in system

95.0 mg

% remaining

100%

24-hour decay curve

Half-life 5h is the common average. Some people clear caffeine in 3h, others in 8–10h (smokers faster, pregnant slower).Tip: <50 mg by bedtime usually means solid sleep.

About this tool

Caffeine's half-life is roughly 5-6 hours but varies a lot by person. Enter what you drank and when, and see how much caffeine is still circulating at any hour. Helps r/Coffee and r/productivity people plan afternoon cups.

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