Health tool
Caffeine timing estimator
Pick a drink and the time you had it. The tool traces how caffeine breaks down and shows the latest sensible time for each common drink tonight.
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Fixed reference: about 50 mg left at bedtime is the level research links to minimal sleep impact for most people.
Caffeine level through the day
The curve adds up every drink decaying over time; the vertical line is your planned bedtime.
Latest sensible time for each drink
Assumes that drink is your only caffeine after that point.
Today's drinks
How the estimate works
Caffeine leaves the body roughly exponentially: every half-life, about half of what is left is cleared. The commonly cited average half-life for healthy adults is about 5 hours, but real values range from 2 to 10 hours between people. Pregnancy, some medications, and genetics can slow it down a lot.
So a 100 mg coffee at 4pm leaves about 40 mg around 11pm with a 5-hour half-life. Whether that matters depends on your sensitivity — people who metabolize slowly often do better cutting off caffeine after lunch.
Frequently asked questions
How long does caffeine take to wear off?
The average half-life in healthy adults is about 5 hours, ranging roughly 2–10 hours between people. Pregnancy, some medications, and genetics can extend it — adjust the half-life to your situation.
Will an afternoon coffee affect tonight's sleep?
It can. With a 5-hour half-life, a 100 mg coffee at 4pm leaves about 40 mg in your system at 11pm — enough to delay sleep for sensitive people.
How much caffeine at bedtime is safe?
Under about 50 mg affects most people little; above 100 mg commonly delays falling asleep. This tool uses 50 mg as the fixed reference level.
What is a safe daily limit?
The FDA and EFSA advise healthy adults stay under about 400 mg per day and 200 mg per serving; during pregnancy, under 200 mg.
How much caffeine is in common drinks?
It varies a lot: an Americano about 80–150 mg, cold brew 150–200 mg, espresso 60–75 mg, bubble milk tea roughly 50–90 mg, Hong Kong-style milk tea over 100 mg, jasmine green milk tea 40–60 mg, lemon tea about 30–50 mg, black tea 40–50 mg, green tea 20–30 mg, cola 30–40 mg, energy drinks 80–160 mg. Brew strength shifts the real numbers.