Caffeine CurveCaffeine Curve Support
Caffeine Curve shows the caffeine that's actually in your system right now, when it clears, and whether your next drink will affect your sleep.
Need help or found a bug?
Email support@caffeinecurve.app or use the contact formand we'll get back to you within a couple of days.
Frequently asked questions
How accurate is the number?
The app models caffeine with a half-life curve. The default half-life is 5 hours; real half-lives vary from person to person (roughly 2–9 hours depending on genetics, smoking, pregnancy, and some medications). You can tune yours in Settings → Half-Life. Presets are included for fast and slow metabolizers, smokers, and pregnancy or birth-control use. The number is an estimate to guide decisions, not a medical measurement.
How do I add the widget?
Long-press your home screen → tap +, search for Caffeine Curve, and pick a size. The medium widget shows your current level plus one-tap log buttons for your most-logged drinks, logging without opening the app. Lock-screen widgets (circular, rectangular, inline) are added from the lock-screen customizer the same way.
Why doesn't the app show a drink I logged from the widget or Siri?
Open the app. It refreshes from the shared log whenever it comes to the foreground. If a drink still seems missing, force-quit and reopen the app, and let us know.
How does Apple Health sync work?
Connect it in Settings → Connect Apple Health. Caffeine Curve then writes your logged drinks to Health as dietary caffeine (write-only; it never reads your Health data). Edits and deletions in the app update Health too. If you declined access earlier, enable it in the Health app: your profile picture → Apps & Services → Caffeine Curve.
Where is my data stored? How do I export or delete it?
On your device, full stop. No account, no cloud, no tracking. You can export a CSV of your entire log from Settings → Export Caffeine Log. Deleting the app deletes all of your data. See the privacy policy.
The sleep-safe warning seems wrong.
The warning compares your projected level at bedtime with your threshold (Settings → Sleep). Check that your bedtime, threshold, and half-life match reality. A longer half-life or lower threshold makes warnings more frequent.
How do I log a drink I forgot earlier?
Open the log sheet and pick a time: 15 minutes, 30 minutes, or an hour ago, or any custom date and time. You can also edit the time (or name and amount) of any existing entry after the fact.
What's the Siri phrase?
Say “Log a drink in Caffeine Curve.” The Log a Drink shortcut takes a drink name and amount, and works from Siri, the Shortcuts app, and widget buttons.