Caffeine Cutoff Calculator
Estimate when to stop caffeine before bed from your bedtime, half-life and a buffer.
Inputs
Result
Visual breakdown
Formula
Cutoff = bedtime − buffer. Remaining % = 0.5^(buffer ÷ half-life). Half-life varies a lot person to person.
Example
Bed 23:00, 5 hr half-life, 8 hr buffer → cutoff 15:00 (~33% of dose still active at bed).
Common examples
Frequently asked
What's a typical caffeine half-life?
Around 5 hours for many adults, but it can range from ~3 to 9 hours depending on genetics, medications, smoking and pregnancy.
Why is a buffer needed?
Even small amounts of caffeine near bedtime can reduce deep sleep. A 6–10 hour buffer is a conservative default.
What if I'm caffeine-sensitive?
Try a longer buffer (10–12 hours), a smaller dose, or earlier last-cup time, and see how sleep responds.
Does this account for tea vs coffee?
No — just timing. A typical cup of tea has roughly half the caffeine of a typical coffee, so dose matters too.
People also calculate
More health →Educational estimate only — caffeine sensitivity varies widely. Not medical advice.