Support

On the main screen, tap + Coffee to log a cup of drip coffee right away, or tap Add Other Drink, then select a drink from the list or enter a custom amount of caffeine in milligrams. The app will immediately begin tracking the decay of that intake.

• Caffeine curve and bedtime estimate — the dashboard shows the caffeine in your body now, a 24-hour forecast graph, how much will remain at your planned bedtime, and when your level will fall below your sleep-ready threshold
• What-if comparison — on the dashboard, add a drink you plan to have and when; for plans today, the app shows how much caffeine would remain at bedtime if you had it. The free version allows 1 plan per day. The add button checks only today's plans: once you have a plan for today, the button opens the Full Access screen, so you cannot add a plan for another day either; if the day you choose already has a plan, Save does not add it. Full Access removes these limits
• Saved drinks — save a custom drink when logging it and reuse it from the top of the logging screen. The free version can keep 1 saved drink; Full Access removes that limit
• Personal half-life — adjust the caffeine half-life used for all estimates between 3 and 8 hours in Settings
• Daily limit — set a daily caffeine limit in Settings; the dashboard shows today's total against it and how many days in a row you stayed under it
• Time to finish — when logging, choose how long you took to drink (all at once, 15, 30, 60 or 120 minutes); the curve spreads the absorption over that time
• Notifications — optional "Daily last call" (each day at the latest time one cup of drip coffee, counted on its own, would leave you under your sleep-ready level by bedtime; caffeine you have already logged that day is not included, so it is a fixed daily guide, not a check of your current level) and an alert when today's total passes your limit. Turn them on in Settings; iOS asks for notification permission
• Trends — the history screen shows 7-day and 30-day totals, the daily average, the change from the previous period and your most consumed drinks
• Apple Health — optional: writes each entry as dietary caffeine (if you allow writing in Health) and reads sleep and resting heart rate to show how they compare on days with more or less caffeine (reference only, not a diagnosis). Turn it on in Settings
• Widgets — Home Screen (small and medium) and rectangular Lock Screen widgets show your current caffeine and the bedtime estimate; the circular Lock Screen widget shows your current caffeine as a gauge against your daily limit; the medium widget has a decay curve, and on iOS 17 or later also quick-add buttons
• Apple Watch — the Watch app shows your current caffeine and the bedtime estimate, and lets you log common drinks
• Siri and Shortcuts — "Check caffeine in CaffeineHalf" and "Log a drink in CaffeineHalf"
• URL scheme — automations can log an intake with caffeinehalf://add?drink=espresso or caffeinehalf://add?mg=80&name=Matcha&minutes=15
• Water — log glasses of water on the dashboard against a daily goal you set in Settings
• AI estimate — on iOS 26 or later, on devices that support Apple Intelligence with Apple Intelligence available, the app can estimate the caffeine of a custom drink from its name, on the device. The result is a rough guide you can edit
• First-time setup — a short setup asks how sensitive you are to caffeine and sets your starting half-life and daily limit (you can change them anytime in Settings)
• iCloud sync — entries, saved drinks and main settings sync between your devices signed in to the same Apple Account

CaffeineHalf uses the standard caffeine half-life of approximately 5 hours by default; you can set it between 3 and 8 hours in Settings. For an intake logged as drunk all at once, the amount rises linearly over the first 45 minutes after the time you entered (a simple absorption model), and then decays exponentially using your half-life. If you set a time to finish (15–120 minutes), the intake is split into 6 equal parts spread evenly over that time, and each part follows the same model. Multiple intakes are added together. The graph shows your estimated caffeine level over time.

CaffeineHalf includes a built-in library of 16 common caffeinated drinks with pre-filled caffeine amounts:

• Coffee: drip coffee, espresso, latte, americano, cappuccino, cold brew, decaf coffee
• Tea: black tea, green tea, matcha, oolong tea, yerba mate
• Others: cola, energy drink, energy shot, dark chocolate

You can also search a list of branded drinks by brand or product name. Brand names and trademarked product names are shown as written; general words in branded drink names, such as “tea bag” or “tablet”, are translated into the app’s language. All amounts are approximate. A branded drink opens as a Custom entry, so you can edit its amount before saving; to log a different amount for one of the 16 built-in drinks, choose Custom and enter the amount.

You can also enter any custom drink with a specific caffeine amount.

Yes. When logging an intake, tap Custom to enter a drink name and its caffeine content in milligrams. To reuse a custom drink, turn on Save this drink before saving the entry (it is off by default). The free version can keep 1 saved drink; Full Access removes that limit.

CaffeineHalf offers a one-time in-app purchase called Full Access. It unlocks unlimited history, CSV export, unlimited saved drinks and multiple what-if comparisons, and removes ads. Open View Full Access in the app, or use Restore Purchases there on a new device. The purchase is processed through the App Store — no subscription required.

CaffeineHalf stores your data on your device. If you are signed in to iCloud with the same Apple Account on both devices, your entries, saved drinks and main settings sync automatically through iCloud. Otherwise, to move your data to a new device, use an iCloud Backup or a Finder/iTunes local backup of your current device, then restore that backup on your new device.

If you set up a new device without restoring from a backup and without iCloud sync (for example, signed in to a different Apple Account or with iCloud turned off for CaffeineHalf), your intake history will need to be entered again.

Yes. Caffeine intake logs are stored on your device (they are included in device backups, and in CSV files if you export them). CaffeineHalf does not send your entries to any server of ours; if you are signed in to iCloud, they sync between your devices through your own iCloud. The free version shows banner ads from Google AdMob, which Google serves according to your consent choices; CaffeineHalf itself has no analytics code, though the Google ad SDKs may collect data as described in the Privacy Policy.

See our Privacy Policy for full details.