# Caffeine mg: Half-life Tracker — Track caffeine, predict sleep

> Track caffeine, predict sleep (iPhone/iPad app by kensuke ueda.)

- Source: https://appshunter.io/ios/app/caffeine-mg-half-life-tracker/id6763047063 (this page in markdown: same URL + `.md`)
- Developer: [kensuke ueda](https://appshunter.io/developer/961845390)
- Category: Health & Fitness, Lifestyle
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 18.0 · 5 MB
- Languages: American English, Japanese
- Released: 2026-04-23
- Data updated: 2026-08-30
- User reviews in markdown: https://appshunter.io/ios/app/caffeine-mg-half-life-tracker/id6763047063/reviews.md

## What is Caffeine mg?

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.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| カフェインmg Pro | $1.99 | one-time |



## Version history (last 5 releases)

### 1.1.10 — 2026-08-29

We improved History to make it clearer that the half-life chart shows how much caffeine
remains at bedtime and when it drops to your sleep-friendly threshold.

### 1.1.9 — 2026-08-04

Pro版の案内を履歴・半減期グラフ・カスタムドリンクの画面から確認できるよう改善しました。あわせて、表示価格と利用状況・診断データの送信処理を改善しました。

### 1.1.8 — 2026-07-24

利用状況データ送信を有効にした場合の計測処理を改善しました。

### 1.1.7 — 2026-07-07

クラッシュ発生時の診断情報を、ユーザー同意後に匿名で送信できる設定を追加しました。入力内容は送信しません。

### 1.1.6 — 2026-06-29

ユーザー同意に基づく匿名の利用状況データ送信設定を追加しました。記録データの入力内容は送信しません。

## More apps by kensuke ueda

- [Mahjong Shanten Calculator](https://appshunter.io/ios/app/mahjong-shanten-calculator/id961845391)
- [PTO Count - Days Tracker](https://appshunter.io/ios/app/pto-count-days-tracker/id6762573639)
- [ビタメモ - サプリ飲み忘れ防止](https://appshunter.io/ios/app/id6762826094)
- [Saketracker: Alcohol log](https://appshunter.io/ios/app/saketracker-alcohol-log/id6763330832)
- [Carmemo - Vehicle service log](https://appshunter.io/ios/app/carmemo-vehicle-service-log/id6763827908)

All apps by kensuke ueda: https://appshunter.io/developer/961845390

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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 2026-08-30.*