Caffeine Cutoff & Half-Life Calculator
See how many milligrams of caffeine remain in your bloodstream at bedtime and find your personal cutoff hour.
What do "half-life" and these cutoff times mean?
Half-life (~5 hours on average) is how long it takes your body to clear half of a caffeine dose. Even if you fall asleep normally, >25–50 mg left at bedtime reduces restorative deep slow-wave sleep.
Half-Caff & Swiss-Water Decaf Options
Keep your afternoon ritual after your caffeine cutoff without elevating circulating adenosine blockers at bedtime.
See Low-Caffeine AlternativesFrequently Asked Questions
Why does this caffeine calculator use a 5-hour half-life?
In healthy adults, hepatic CYP1A2 enzymes eliminate roughly half of absorbed caffeine every 5 hours on average (ranging from 3 to 7 hours depending on genetics and medications).
How much residual caffeine at bedtime still disrupts deep sleep?
Even if you fall asleep normally, more than 50 mg to 100 mg of active caffeine at lights-out reduces restorative slow-wave N3 sleep and increases nighttime micro-awakenings.
What is a safe daily caffeine cutoff time for a 10:30 PM bedtime?
With a 5-hour half-life, stopping coffee or pre-workout 9 to 10 hours before bedtime (around 12:30 PM to 1:30 PM) ensures roughly two half-lives of clearance before sleep.
Optimize the rest of your 24-hour sleep routine
Pair your cycle window with caffeine timing, power naps, or weekly sleep debt tracking.