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Caffeine Calculator
Add up the caffeine in your drinks and see how much may still be in your body at bedtime.
Daily caffeine
Total today: 0 mg
Guidance check: —
Estimated at bedtime: —
How to use the Caffeine Calculator
- Choose a drink from the list and set how many servings you had.
- Click Add drink to build up the total for the day.
- Set the current hour and bedtime to estimate what is left in your body.
Features
- Twelve common drinks with typical caffeine amounts
- Running total compared with the 400 mg adult guidance
- Five hour half-life estimate for bedtime
- Full breakdown of every drink you logged
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Frequently Asked Questions
Common questions about the free online caffeine calculator.
Many health bodies suggest up to 400 mg a day for healthy adults, which is roughly four cups
of filter coffee.
A 240 ml filter coffee has about 95 mg, an espresso around 63 mg, and instant coffee roughly
62 mg per cup.
The average half-life is about five hours in adults, so half the caffeine is gone five hours
after a drink.
Caffeine blocks adenosine, the chemical that builds up sleep pressure, so a late drink can
delay how quickly you fall asleep.
The total is halved once for every five hours between now and bedtime, which gives a rough
remaining amount.
Yes. Pregnancy, some medicines and certain heart conditions call for lower limits, so ask a
clinician about your own case.
No. The caffeine figures are an estimate for general information and not medical advice, so
speak to a doctor about your own limits.
Yes. The caffeine calculator is completely free, runs locally in your browser and needs no
account or sign-up.
Last updated: October 10, 2026