Cafactor vs Caffeine Clock
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Cafactor
This app models your body's real-time caffeine levels using a scientific pharmacokinetic approach. It helps you understand your caffeine absorption, decay, and personal sleep thresholds, adapting to your unique biology and activity. Connect with health data for an even smarter metabolic coaching experience.
- 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
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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.
Caffeine Clock
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Not how much you drank - how much is still in you now, and how much will still be there at bedtime. One tap to log Set up to four usual drinks and log them the moment you tap. Mistaps are undoable, and you can move a record to "1 hour ago" afterwards. The hours you could not see The ring at the centre - the Caffeine Halo - shows what is estimated to remain. It also shows the estimate at your bedtime and when it will be mostly gone. Connect Health (Pro) Compare the estimate at bedtime with your time asleep, night wakings, and next-morning HRV, using your records only. The analysis stays on this device and is never sent anywhere. Widgets and Apple Watch Check from the Lock Screen, Home Screen, or your watch face - and log right there. Apple Watch logs offline and syncs later without duplicates. Two themes Calm roast and crema tones, or a dark base with electric accents. Switch any time in Settings. Never blames you Days without records are not failures. No streak pressure, and notifications carry neutral wording only. No account No sign-in. Your records stay on your device. Caffeine Clock Pro (one-time purchase) unlocks sleep relations, every widget, Apple Watch, custom presets, and CSV export. Logging, estimates, the calendar, and today's and weekly stats stay free. Note: caffeine amounts shown are estimates, not measurements. Do not use them for medical, medication, or driving decisions.
Screenshots
Verdict
The clearest difference is update cadence: Caffeine Clock at every 2 days against Cafactor's weekly. On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Cafactor sells 1 one-off in-app purchase and Caffeine Clock sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
Cafactor ships an update weekly, Caffeine Clock every 2 days. The most recent releases landed on September 9, 2026 and September 8, 2026 respectively.
| Parameter | Cafactor | Caffeine Clock |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Weekly | Every 2 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Freemium | — |
| Devices | iPhone, iPad, Apple Watch — better | iPhone, Apple Watch |
| Requires iOS | 17.6 — better | 18.0 |
| Further details — not scored | ||
| Size | 9 MB | 6 MB |
| Age rating | 4+ | 12+ |
| Developer | Nan Yu | kazunari aoki |
In-app purchases
Cafactor
- Cafactor Pro$3.99
Caffeine Clock
- Caffeine Clock Pro$9.99







