Cafactor

Track caffeine. Protect sleep.

Free · In-App Purchases · Designed for iPad. Not verified for macOS.

Caffeine Hourglass is now Cafactor — rebuilt from the ground up. What began as a simple caffeine timer has evolved into a full physiological model that adapts to your biology in real time. Version 2.0 isn't an update. It's a new category of health tool. Know your caffeine. Protect your sleep. Log a drink in seconds. Cafactor computes your real-time caffeine curve using a peer-reviewed pharmacokinetic model — complete with a realistic absorption phase, first-order decay, and your personal biological parameters. See whether you can safely have one more coffee, and exactly when your levels will drop below your personal sleep threshold. Personalised to your body Set your sex, height, weight, and age. Cafactor applies the Boer (1984) lean-body-mass formula to calculate how caffeine distributes in your specific body. Add smoking status, hormonal medication, or pregnancy for a half-life that's truly yours. Your tolerance to caffeine — derived automatically from 7-day history — rounds out the picture. HealthKit: exponentially smarter Connect Apple Health and Cafactor transforms from a tracker into an adaptive metabolic coach: • Exercise modifier — Recent vigorous workouts temporarily speed up your metabolism. Cafactor detects this from HealthKit and adjusts your decay curve automatically. • Sleep-adaptive threshold — Last night's poor sleep tightens your safe window today. Great sleep? More room for your morning ritual. • HRV & Recovery (Apple Watch) — Daily heart-rate variability fuses with sleep quality to create a PhysiologicalState score, shifting your optimal intake windows and adjusting thresholds by up to 40%. • Progressive calibration — Recency-weighted regression over 30 days of sleep and HRV feedback automatically refines your personal half-life, growing from Preliminary to Reliable confidence as data accumulates. Pro features Unlimited history · Trend, sleep quality and scatter charts · Last safe caffeine time · Four smart notifications (morning window, safe window, withdrawal, recovery) · Shareable weekly report · Siri shortcuts · Unlimited custom drinks Free, forever, offline Core tracking is always free. No account. No internet. No data leaves your device — ever.

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bug fixed

Version 2.0.2

The developer, Nan Yu, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

    Privacy practices may vary based, for example, on the features you use or your age. Learn More

    Accessibility

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    Information

    Size
    • 9.2 MB
    Category
    • Health & Fitness
    Compatibility
    Requires iOS 17.6 or later.
    • iPhone
      Requires iOS 17.6 or later.
    • iPad
      Requires iPadOS 17.6 or later.
    • Mac
      Requires macOS 14.6 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.3 or later.
    • Apple Watch
      Requires watchOS 26.2 or later.
    Languages
    English and 26 more
    • English, Arabic, Croatian, Czech, Danish, Dutch, Finnish, French, German, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Norwegian Bokmål, Polish, Portuguese, Romanian, Russian, Simplified Chinese, Spanish, Swedish, Traditional Chinese, Turkish, Ukrainian
    Age Rating
    9+
    In-App Purchases
    Yes
    Provider
    Nan Yu
    • Nan Yu has not identified itself as a trader for this app. If you are a consumer in the European Economic Area, consumer rights do not apply to agreements between you and the provider.
    Copyright
    • © 2026 Yu. All rights reserved.
  • Developer Website
  • Privacy Policy

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