CaffeTrack - Caffeine Tracker & Metabolism Graph
CaffeTrack keeps a running tally of the caffeine you drink and turns it into a picture you can actually use. Each time you log a coffee, tea, cola or energy drink, the app estimates how much caffeine is still in your system right now and draws a curve for the next 12 hours, so you can see whether that late afternoon latte will still be hanging around at bedtime.
It suits anyone who wants to cut back, sleep better or simply understand their own habits: students on exam weeks, shift workers, people who have been told to watch their intake, or anyone who has lost count of refills. You set a daily limit, and the home screen shows how close you are to it.
The tracker runs in your browser without an account. Your drinks, settings and history are kept on this device only.
The app runs entirely in your browser. What you enter is saved only on this device.
How to use CaffeTrack
- Go through the welcome screens. A short introduction explains the main ideas. You can skip it at any time.
- Add your first drink. Tap the add button and choose a category: coffee, tea, energy drinks, soda or other. Pick a drink, select a serving size and adjust the time if you had it earlier.
- Save favourites. Tap the heart on drinks you have often. They appear in a Favourites tab so logging takes a couple of taps.
- Create custom drinks. If your usual drink is not listed, add it with your own name and caffeine amount. Packaging or the cafe's website usually gives the figure.
- Read the home screen. You will see the estimated caffeine remaining now, a level indicator, today's total against your daily limit and the 12-hour metabolism prediction graph.
- Personalise the estimate. In settings you can enter gender, age and weight, and mark whether you are pregnant, nursing or a smoker. Age, weight and those three options adjust the half-life used in the calculation. You can also change the daily limit and theme.
- Review history and statistics. History lists every entry by day and lets you edit or delete one. Statistics shows totals, daily averages, your highest day and your most logged drinks over 7, 30 or 90 days or a year.
Features
- Estimate of caffeine remaining in your body, updated from every logged drink
- Prediction graph for the next 12 hours
- Daily total compared with an adjustable limit (400 mg by default)
- Presets for drip coffee, espresso, lattes, several teas, colas, energy drinks, cocoa and caffeine tablets
- Custom drinks and a favourites list
- Half-life adjusted for pregnancy, nursing, smoking, age and body weight
- Editable history grouped by day
- Statistics for 7, 30 and 90 days and one year, including a top drinks ranking
- Light, dark or system theme
Understanding caffeine half-life and daily intake
What half-life means
Your liver clears caffeine at a fairly steady proportional rate. The half-life is the time it takes for the amount in your blood to fall by half. In healthy adults it is often quoted at around five hours, but individual values commonly range from roughly two to more than eight hours. CaffeTrack starts from 5.5 hours and applies the formula: remaining = amount taken × 0.5 ^ (hours elapsed ÷ half-life).
In practice that means a 160 mg coffee at 2 pm leaves about 80 mg at 7:30 pm and about 40 mg around 1 am. Several drinks stack on top of each other, which is why the curve can stay high all afternoon even if each cup feels modest.
Why the estimate is personal
Some factors are well known to change caffeine clearance. Pregnancy slows it considerably, especially later in pregnancy. Smoking tends to speed it up. Older adults and people with liver conditions usually clear it more slowly, and some medicines, including certain oral contraceptives and antidepressants, can roughly double how long it lasts. Genetics also play a big part. CaffeTrack's adjustments for pregnancy, nursing, smoking, age and weight are simple multipliers meant to nudge the estimate, not to measure you.
How much is commonly considered moderate
Health agencies in the US and Europe describe up to about 400 mg per day as generally not associated with harm for most healthy adults. Lower amounts are usually advised during pregnancy and breastfeeding, and for teenagers and children, and some people feel jittery or anxious on far less. If you are pregnant, have a heart condition, high blood pressure or anxiety, or take medication, ask a doctor or pharmacist what is right for you.
Caffeine and sleep
Even when you fall asleep easily, caffeine still in your system can make sleep lighter and shorter. A useful habit is to look at the graph before your last drink of the day and check how much would be left at your usual bedtime. Many people find that moving their final coffee to before mid-afternoon makes a noticeable difference.
Caffeine content varies
Preset values are typical figures. A cafe drip coffee can contain much more or less than a home brew depending on beans, grind and cup size, and tea strength depends on steeping time. For packaged drinks, the label is the most reliable number.
Frequently asked questions
Where is my data kept?
In this browser on this device only. There is no account and nothing is uploaded. If you clear your browser's site data or use private browsing, your drinks and settings will be erased, and they will not show up on other devices.
How accurate is the caffeine remaining figure?
It is an estimate from a standard half-life model and typical caffeine amounts. Real metabolism differs a lot from person to person, so use it to spot patterns rather than as a measurement.
Can I change the 400 mg limit?
Yes. Open settings and set your own daily limit. The home screen will show a caution when today's total goes over it.
Can I fix a drink I logged by mistake?
Open History, find the entry and edit the amount or time, or delete it. There is also an option to clear all records.
What does the iPhone and Android app add?
The phone app can send notifications, such as a warning a set number of hours before bedtime, an alert when you near your daily limit, and a note when caffeine has dropped to half or has cleared. The web version cannot send notifications, though you can still set a bedtime there.
Are caffeine tablets included?
Yes, there are presets for 50 mg, 100 mg and 200 mg tablets, and you can add any product as a custom drink.
Limitations of the web version
- No notifications or bedtime warnings on the web
- Estimates use a general model and typical drink values
- Data is stored in one browser with no backup or sync
Disclaimer
CaffeTrack provides estimates based on a general half-life model; actual caffeine metabolism varies greatly between people. It is not a medical device and does not provide medical advice. If you are pregnant, breastfeeding, have a health condition or take medication, consult a doctor about caffeine intake.
Phone app
CaffeTrack is also available as an app for phones and tablets: