Caffeine Cutoff Calculator

Enter your bedtime and what you drank today. See how much caffeine is still working when the lights go out — and what time your last drink should have been.

Caffeine half-life varies widely between individuals — genetics, smoking, oral contraceptives, pregnancy, and liver function all shift it. This calculator uses population averages, so treat the result as a starting point and adjust based on how you actually sleep.

General information, not medical advice. If you have a heart condition, a sleep disorder, an anxiety disorder, or are pregnant or nursing, talk to your doctor about caffeine. The FDA considers up to 400mg per day safe for most healthy adults.