Caffeine & water, calculated for you
Know your coffee.Know your limit.
Caffculator tracks every cup, estimates how much caffeine is still in your body, sets a daily limit from your weight and tells you how much water to drink with it. No sign-up, no email.
- Free
- Private by design
- iOS & Android
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5.7mg / kg
Your personal daily limit, capped at 400 mg
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5hours
Average caffeine half-life we use to model your body
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50mg
Bedtime target so caffeine doesn’t steal your sleep
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33ml / kg
Base water need, plus 200 ml for every cup
HOW IT WORKS
Three taps a day. Zero guesswork.
Log what you drink, and Caffculator does the math: what’s left in your body, how close you are to your limit and how much water balances it.
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Log your cup
Pick a drink, adjust the size and time. Espresso, latte, Turkish coffee, tea or your own custom drink.
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See what’s still in you
A live curve shows the caffeine in your body right now and how much will be left at bedtime.
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Balance with water
Your water goal grows with every cup, so you stay hydrated without doing the math.
FEATURES
Built around your body, not a generic number.
Every number in Caffculator comes from your weight, your sensitivity and your sleep schedule.
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Personal daily limit
Weight × 5.7 mg, never above 400 mg. Lower limits for pregnancy or when your doctor says so.
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Sleep-safe timing
See how much caffeine will be left at bedtime and when your last cup should be.
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Water balance
A daily water goal that adapts to how much coffee you drink.
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Habits & insights
Weekly trends, your busiest coffee hour and gentle nudges to cut back.
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Private by design
No account, no email, no name. Your data stays tied to an anonymous ID.
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Smart reminders
Gentle nudges to drink water and a heads-up before a late-night coffee.
THE SCIENCE
Open formulas. No black box.
Caffculator uses published guidance and shows you exactly how every number is calculated.
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Daily limit
weight × 5.7 mg · max 400 mg
EFSA considers up to 400 mg a day safe for healthy, non-pregnant adults, and 200 mg during pregnancy.
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Caffeine in body
left = taken × 0.5^(hours ÷ 5)
Half-life varies from person to person (typically 3–7 h); we use an average of 5 h.
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Sleep threshold
at bedtime < 50 mg
A practical target you can change in settings.
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Water goal
weight × 33 ml + 200 ml per cup
A simple rule of thumb. We add a little extra per cup to keep you on the safe side; needs also rise on hot days and when you work out.
Source: EFSA, Scientific Opinion on the safety of caffeine (2015). Caffculator does not give medical advice.
Do I need to create an account?
No. You can start right away without signing up — no email, no password. If you want to keep your data safe or use it on another device, you can optionally connect Apple, Google or your email.
How is my daily limit calculated?
Your weight × 5.7 mg, rounded to the nearest 10 and never above 400 mg. Under 18, it’s your weight × 3 mg. It drops to 200 mg if you’re pregnant, breastfeeding or your doctor has asked you to cut back. If you tell us caffeine hits you harder than most, we lower it by 25%. You can also set your own limit.
Is Caffculator medical advice?
No. Caffculator gives general estimates based on published guidance. Everyone processes caffeine differently; if you have a health condition, are pregnant or take medication, ask your doctor.
Which drinks can I track?
Espresso, Americano, filter coffee, latte, cappuccino, tea, Turkish coffee, cola, energy drinks and more. You can also add your own drinks with their own caffeine amount.
Is it free?
Yes, Caffculator is free. Every feature is included.
Your next cup,calculated.
Free on iOS and Android. Set up in under a minute.
