See it leave
your bloodstream.
Caffeine does not just vanish when the cup is empty. It lingers for hours on a predictable curve. Log what you drink and watch the milligrams rise and fall in real time, so you know exactly when you are clear for sleep.
What is in your system right now.
Tap what you drank and when. The chart plots your caffeine rising and decaying across the day, with your sleep cutoff marked. Everything is saved on this device.
The model uses a 5-hour half-life, the population average. Yours may run faster or slower depending on genetics, smoking, pregnancy and medication. Adjust it in the Half-Life section to personalise every curve on this page.
Your last cup, timed.
Caffeine close to bed wrecks deep sleep even when you fall asleep fine. Set your bedtime and the size of your drink to find the latest moment you can safely have it.
How much is too much?
Health authorities cap healthy adults at 400 mg a day, but your body weight sets a tighter, more personal ceiling. Move the sliders to see yours.
Why one cup lasts half the day.
Caffeine clears on an exponential curve. After one half-life, half remains; after two, a quarter. Set your personal half-life and watch how a single 95 mg coffee fades.
one 95 mg coffee at hour 0
How much is in your drink?
Typical caffeine content of common drinks, foods and supplements. Sort by any column, filter by type, or tap a row to log it straight into your tracker.
| Source | Serving | Caffeine | Per 100 ml | Log |
|---|
Numbers vary a lot by brand and brew. A strong independent coffee can hold double a typical drip cup, and energy drinks range widely. Treat these as solid averages, not exact label values.
The many faces of one molecule.
The caffeine in an espresso, an energy shot and a square of dark chocolate is chemically identical. What changes is the dose, the speed and the baggage it arrives with. Tap a form.
What caffeine actually does.
Plain-language deep dives into the pharmacology of the world's favourite drug. Tap any card to expand it.
The same cup hits everyone differently.
Your genes, habits and biology decide how fast caffeine clears, which is why one espresso wires your friend and does nothing to you. Tap a factor.
Benefits, risks and the sweet spot.
Caffeine is genuinely useful and genuinely overdone. Here is the honest ledger, plus the warning signs you have had too much.
A short history of the buzz.
Caffeine has shaped trade, revolutions and daily ritual for over a thousand years. Tap a card for the story behind the cup.
One molecule, a thousand rituals.
Every culture has its own way of taking caffeine, from a thimble of Turkish coffee to a gourd of mate. Tap a card to travel.
Caffeine, hour by hour.
A flexible template for getting the lift when you need it and clearing it in time for sleep. Adjust to your own wake and bed times.
Why the world runs on it.
Used in moderation, caffeine earns its place. These benefits are genuine and well studied, not marketing. Tap a card for the evidence.
What caffeine does to each part of you.
The lift you feel in your head is only part of the story. Caffeine touches systems all over the body. Tap a card.
Caffeine plus everything else.
Caffeine is usually mixed with other substances, for better or worse. Here is how the common pairings actually play out. Tap a card.
The cycle of needing more.
Regular use builds tolerance, and stopping brings real withdrawal. Understanding the cycle is the key to using caffeine deliberately instead of being used by it.
Who should go easy.
For most healthy adults caffeine is fine in moderation. For some groups the limit is lower or the risks higher. Tap a card.
Caffeine for the day you are having.
Theory is easy, real life is messy. Here are practical playbooks for the moments where caffeine timing actually matters. Tap any card.
What you have heard versus the evidence.
Caffeine is wrapped in folklore. Here are the common myths, each paired with what the science actually says.
Habits of a smart caffeine user.
The difference between caffeine working for you and against you is mostly timing and dose. These are the habits that keep it an asset.
The whole thing on one card.
If you remember nothing else, remember these. The fast rules of caffeine, distilled.
Caffeine, answered.
The questions people actually ask, answered from current pharmacology and nutrition consensus.
The glossary.
Every term used on this page, defined in one breath.
Grounded in real guidance.
The figures and advice here reflect mainstream pharmacology, nutrition and sleep-science consensus. These are the kinds of authoritative bodies that set it. Defer to your own clinician for personal medical advice.