Caffeine Cutoff Calculator
Find your caffeine cutoff time: enter bedtime, dose and sensitivity to see when the last coffee should be, based on a 5-hour half-life.
About this tool
Caffeine does not just keep you awake — it suppresses deep sleep for hours after the last cup. This calculator works backwards from your bedtime using the standard 5-hour half-life.
Set the cutoff, protect your deep sleep, and the morning coffee works better because you actually rested. Small change, disproportionate effect on how the day feels.
FAQ
How long does caffeine last?
Half-life averages about 5 hours, so 200 mg at 3 pm leaves roughly 50 mg at 11 pm — enough to reduce deep sleep.
Why does sleep quality matter more than sleep length?
Caffeine mainly cuts deep sleep. You can sleep 8 hours and still wake unrested if the first half was light.
What time should I stop?
Most people: no caffeine after 2 pm for an 11 pm bedtime. Slow metabolizers should shift that earlier, or accept a lighter sleep.