Caffeine Half-Life Calculator
Estimate how much caffeine remains at bedtime, find an input-based caffeine cutoff time, and explore a half-life decay timeline for today's drinks.
Caffeine calculator FAQ
How long does caffeine stay in your system?
Caffeine has an average half-life of about five hours in healthy adults. That means roughly half of a dose may remain after five hours and one quarter after ten hours, although individual clearance varies.
What is a caffeine cutoff time?
A caffeine cutoff time is the latest estimated time for another dose while staying within the calculator's bedtime planning target. It depends on your existing intake, the next dose, and your target bedtime.
How accurate is this caffeine calculator?
It is a planning estimate based on a five-hour half-life, not a measurement of your body. Genetics, pregnancy, smoking, medications, liver health, and other factors can change caffeine metabolism.
Does CaffCutoff store my caffeine data?
No. The calculator runs in your browser without an account, backend, or database. A result is passed to the report page in the local URL and is not sent to CaffCutoff.