Comparison

Cafactor vs Caffeine mg

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • 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
Features
Read full description

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.

About

Caffeine mg

Features
Read full description

Caffeine mg is a one-tap caffeine tracker that visualises remaining body caffeine and the time it drops below a sleep-friendly threshold using a half-life decay model. "Can I have one more coffee this afternoon and still sleep tonight?" — that's the question this app answers. ■ Who it's for - Daily coffee or energy drink consumers - People whose afternoon caffeine affects sleep - Users who prefer no ads and one-time purchases - Login-free tracking with caffeine records stored on device ■ Main features - 50+ preset drinks (coffee, energy drinks, tea, etc.) - Custom drinks with caffeine content and serving size - Tap to log "now", long press to set the time - Today's total intake and remaining allowance (400mg default) - Half-life decay simulation - Home screen widget for one-tap logging - Siri / Shortcuts support - Last 7 days of history ■ iOS 18 features (Pro) - Live Activity + Dynamic Island for body caffeine + sleep-friendly time - Lock Screen Control + Control Center for one-tap logging - Action Button on iPhone 15 Pro and later - Half-life simulation chart ■ Pro (one-time, JPY 370) - Unlimited custom drinks - Live Activity / Dynamic Island - Lock Screen Control - Action Button integration - Full history + CSV export - Medium / Large widgets ■ Why we made it - Free to start (50+ presets + 3 custom drinks) - No login, no account - Caffeine records stay on device; anonymous usage events are optional - No subscription. Pro is one-time only. - Zero ads. ■ Science - Daily upper limit 400 mg (WHO / FDA / EFSA / Health Canada / Japan MHLW Sleep Guidelines 2023 consensus) - 50 mg "sleep-friendly residual" threshold per Japan MHLW Sleep Guidelines 2023 - Default half-life is 5 hours (individual range 3-7 hours) - All thresholds adjustable in Settings ■ Requirements - iOS 18.0 or later (for Live Activity / Lock Screen Control / Action Button) This app is intended as a caffeine intake tracker. It does not provide medical advice, diagnosis, drug-interaction checks, or individualised guidance for pregnant users, users with cardiac conditions, etc. Please consult a doctor or pharmacist for health decisions.

Screenshots

Cafactor4 screens
Caffeine mg4 screens

Verdict

The call

The clearest difference is device support: Cafactor at 3 against Caffeine mg's 1. On price, update cadence, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Cafactor sells 1 one-off in-app purchase and Caffeine mg sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly weekly. The most recent releases landed on September 25, 2026 and September 20, 2026 respectively.

Scorecard1 real difference · 9 level
Cafactor versus Caffeine mg: the parameters behind the verdict, then further details
ParameterCafactorCaffeine mg
PriceFreeFree
Rating5.0 (1 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings1 — better—
Update frequencyWeeklyWeekly
AdsNoNo
In-app purchasesYesYes
MonetizationFreemium—
DevicesiPhone, iPad, Apple Watch — betteriPhone
Requires iOS17.6 — better18.0
Further details — not scored
Size9 MB5 MB
Age rating4+4+
DeveloperNan Yukensuke ueda

In-app purchases

1 purchases

Cafactor

One-time1
  • Cafactor Pro$3.99
1 purchases

Caffeine mg

One-time1
  • カフェインmg Pro$1.99

Questions

Is Cafactor free?
Cafactor is free to download, with in-app purchases available.
Is Caffeine mg free?
Caffeine mg is free to download, with in-app purchases available.
Do Cafactor or Caffeine mg have ads?
Neither Cafactor nor Caffeine mg shows ads.
Which is updated more often, Cafactor or Caffeine mg?
Cafactor ships an update weekly, and Caffeine mg weekly. Most recently, Cafactor was updated on September 25, 2026 and Caffeine mg on September 20, 2026.

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