When should you stop drinking coffee today?
Tell us your bedtime and what you drink. We run the half-life clock backward and give you a time: your last cup.
Your last drip coffee is 3:15 pm.
That's 7 hours 45 minutes before your 11:00 pm bedtime — time enough to wear down to your 50 mg line.
Caffeine sensitivity varies — if you're pregnant or on medication, ask your doctor. This tool assumes a typical healthy adult.
What the tool is doing
One well-known fact does all the work: caffeine wears off by halves, with a typical half-life of about five hours. Instead of showing you a chart and leaving you to squint, we run that clock backward from your bedtime — how early must the cup land so that, by lights out, what's left is small enough to sleep on? That time is your last call. The curve above shows the same answer as a picture: finish your drink on the lamp-lit line and you glide down to your bedtime line right as the moon comes up.
The FDA puts the typical caffeine half-life at four to six hours; most people land near five. For the day as a whole, the FDA's guide is 400 mg for healthy adults — about four small cups of drip. The how-it-works page walks through the arithmetic and every source.
Common questions
When should I stop drinking coffee before bed?
For a full cup of drip, most people land somewhere in the early-to-mid afternoon — six to eight hours before bed. Where exactly depends on the drink, the day, and you, which is what the tool above works out: it takes your bedtime and your drink and hands back a clock time.
Why does a 3 pm coffee keep me up at 11?
Caffeine leaves by halves, not all at once. Half of a 3 pm cup is still with you around 8 pm, and a quarter of it is still working at 1 am. You fall asleep eventually — just lighter and later than you meant to.
What counts toward the cutoff besides coffee?
Anything with caffeine in it: black and green tea, colas, energy drinks, yerba mate, even dark chocolate. An afternoon Celsius carries more caffeine than most large coffees. The drinks page lists real numbers for about forty of them, each with its source.
Is one number right for everyone?
No — and the tool doesn't pretend it is. It runs on the typical five-hour half-life from the FDA's four-to-six-hour range, and lets you pick how protective to be at bedtime. If you're pregnant, on medication, or just know caffeine hits you hard, your range is different: ask your doctor.