# Cafactor — Track caffeine. Protect sleep.

> Real-time caffeine tracking and sleep protection based on physiological modeling. (iPhone/iPad app by Nan Yu.)

- Source: https://appshunter.io/ios/app/cafactor/id6757445668 (this page in markdown: same URL + `.md`)
- Developer: [Nan Yu](https://appshunter.io/developer/1559044036)
- Category: Health & Fitness, Food & Drink
- Price: Free with in-app purchases
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 17.6 · 9 MB
- Languages: American English, Arabic, Croatian, Czech, Danish, Dutch, Finnish, French (France), German (Germany), Hebrew and 17 more
- Released: 2026-01-09
- Data updated: 2026-08-17
- Monetization: freemium
- User reviews in markdown: https://appshunter.io/ios/app/cafactor/id6757445668/reviews.md

## What is Cafactor?

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.

## Key features

- Real-time caffeine curve modeling
- Personalized physiological parameters
- HealthKit integration for adaptive coaching
- Exercise and sleep-adaptive thresholds
- HRV & Recovery integration
- Progressive calibration of half-life
- Offline, private tracking

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Cafactor Pro | $3.99 | one-time |


## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/cafactor/id6757445668/reviews.md

### 5/5 — 很实用

*2026-01-13*

超级实用的一个软件，对咖啡因依赖的人群非常的好用。

## Frequently asked questions about Cafactor

### Does Cafactor have ads?

No, Cafactor is ad-free. The core tracking functionality is always free and does not contain advertisements.

### How accurate is Cafactor's caffeine modeling?

Cafactor uses a peer-reviewed pharmacokinetic model and personal biological parameters to compute your real-time caffeine curve. It incorporates factors like absorption, decay, and personal physiology for realistic estimations.

### What personal data does Cafactor use?

Cafactor uses your sex, height, weight, age, smoking status, hormonal medication, and pregnancy status to calculate how caffeine distributes in your body. It also derives your tolerance from a 7-day history.

### How does Cafactor integrate with Apple Health?

When connected to Apple Health, Cafactor acts as an adaptive metabolic coach. It uses exercise data to adjust your decay curve, sleep quality to modify your safe window, and HRV & Recovery to create a PhysiologicalState score.

### What are the Pro features in Cafactor?

Pro features include unlimited history, trend and scatter charts, last safe caffeine time, four smart notifications, shareable weekly reports, Siri shortcuts, and unlimited custom drinks.

### Is Cafactor available on Android?

Based on the provided data, Cafactor is supported on Apple Watch, iPhone, and iPad, indicating it is an iOS-exclusive application.

### How often is Cafactor updated?

The latest version of Cafactor is 2.0.4, which was last updated on May 5, 2026. This suggests a commitment to regular updates and improvements.

### What is the age rating for Cafactor?

Cafactor has an age rating of 4+, making it suitable for a wide range of users. The app focuses on health and fitness tracking.

## Version history (last 5 releases)

### 2.0.4 — 2026-05-05

Added an Imperial Units toggle in Settings. 
When enabled, body weight switches to lbs, height to inches, and drink volumes to fl oz, all display-only conversions, with no changes to your existing data.

### 2.0.3 — 2026-04-29

Fixed an issue where caffeine intake reminders sometimes failed to fire on schedule.

### 2.0.2 — 2026-03-28

bug fixed

### 2.0.1 — 2026-03-25

bug fixed

### 2.0.0 — 2026-03-17

Cafactor (formerly Caffeine Hourglass) is a complete reinvention.

New identity
• App renamed from Caffeine Hourglass to Cafactor
• Redesigned interface with real-time decay animation and absorption indicator

Personalised biology
• Threshold now adapts to body composition (lean body mass via Boer formula), age, and habitual tolerance
• Smoker / hormonal medication / pregnancy half-life modifiers carried forward and expanded

HealthKit integration
• Exercise modifier: vigorous workouts temporarily shorten your half-life
• Sleep-adaptive threshold: last night's sleep adjusts today's safe limit
• HRV & Recovery (Apple Watch): daily HRV fuses with sleep for dynamic caffeine windows
• Progressive half-life calibration using sleep + HRV regression (confidence: Preliminary → Reliable)

Pro tier
• Unlimited history with weekly, monthly, yearly trend charts
• Last safe caffeine time (binary search, personalised)
• Safe window, morning reminder, withdrawal alert, and recovery alert notifications
• Shareable weekly report card
• Siri Shortcuts: "Log a drink" / "Check my caffeine"
• Unlimited custom drink presets

Apple Watch
• Companion app: real-time caffeine ring, safe cutoff time, today's total, bedtime prediction, quick-log from wrist

History view
• Sleep quality ring, HRV baseline chart, calibration scatter plot (caffeine vs. actual sleep)
• Pro date picker with full history access

Guided onboarding — 3-screen setup on first launch

## More apps by Nan Yu

- [浑水摸鱼](https://appshunter.io/ios/app/id1362935586)
- [Renobo: Ebook & Manga Reader](https://appshunter.io/ios/app/renobo-ebook-and-manga-reader/id1575881378)
- [Post Rush](https://appshunter.io/ios/app/post-rush/id6757679826)
- [Floor 73](https://appshunter.io/ios/app/floor-73/id6759790029)
- [CíBuch 中德词簿](https://appshunter.io/ios/app/cibuch/id6761343922)

All apps by Nan Yu: https://appshunter.io/developer/1559044036

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-17.*