Daily Caffeine Cutoff Curve
When does your coffee actually wear off? Add your day's drinks and your bedtime to see how much caffeine is still active at lights-out, the range your body might really be in, and your personal last call for a caffeine-quiet night.
400 mg
for healthy adults — FDA & Health Canada
~5 hours
individual range runs 2–12 hours
≈50 mg
at bedtime — from sleep-latency research
Caffeine leaves your system by halves: roughly every 5 hours, your body clears half of what's left. A 150 mg latte at 3 p.m. is still ~75 mg at 8 p.m. and ~50 mg near a typical bedtime. The curve adds every drink in your day together — and because clearance genuinely varies from person to person (about 2 to 12 hours), we draw a range, not a single confident line.
The half-life math means an afternoon coffee is, in effect, a bedtime-adjacent dose — sleep research associates meaningful caffeine at lights-out with taking longer to fall asleep and lighter sleep. Your curve computes a personal "last call": the latest a standard coffee still fades below the sleep-sensitivity guide by your bedtime.
This tool is educational, not medical advice. Caffeine values come from brand and USDA sources; clearance modeling uses published pharmacokinetics with individual variation shown as a range. Nothing you enter is stored — inputs live only in this page's URL.