A caffeine tracker that shows what is still in your system and when your last coffee has to be
Caffeine Tracker: Curfew estimates the caffeine active in your body from what you logged, using a half-life model (about 5 hours for most adults, adjustable). Log espresso, drip, latte, tea, matcha, energy drinks and more in two taps, watch a 12-hour curve, keep today under 400 mg, and set a bedtime with a target (25, 50 or 100 mg) to get a curfew: the latest time for your last drink. It works offline with no account. A one-time Pro unlock adds Apple Health sync, 30-day history and custom drinks.
- Price
- Free. One-time Pro unlock, no subscription
- Model
- Half-life decay, 2.5 to 8 h, default 5 h
- Drinks
- 21 presets with typical mg, small / regular / large, custom with Pro
- Privacy
- Offline, no account; Apple Health write only if you turn it on
What you get: the number that matters now, a curfew for tonight, and a week you can read
How to find your caffeine cutoff time
The question is not how much coffee you drink, it is how much is left when your head hits the pillow. Three settings and the app does the math.
- Set your bedtimeSettings → Sleep → Bedtime. The app always aims at tonight's bedtime, even if you log a late drink after midnight.
- Pick how much you can sleep on25 mg if you are a light sleeper, 50 mg for most people, 100 mg if caffeine barely affects you. This is the target level at bedtime.
- Log what you drinkTap a drink on the home screen (espresso, drip, latte, tea, energy drink) or open the full list with sizes and a time picker for the cup you forgot.
- Read the curfewThe Bedtime curfew card says, for example, "Last 95 mg drink by 3:40 PM to be under 50 mg at bedtime." After that time it tells you what another cup would leave in you at bedtime.
Built around one number: what is active right now
☕Live level
Every dose decays with a half-life model. See the milligrams active now, a status (clear, active, wired) and how long until you are below your bedtime target.
🌙Bedtime curfew
Latest time for your usual drink so you are under your target at bedtime. Adjustable half-life for pregnancy, medication or fast metabolisers.
⚡Two-tap logging
Six favourites on the home screen; 21 presets with typical caffeine contents; small, regular and large; backdate a drink.
📊Daily limit and history
Progress against 400, 300 or 200 mg. Seven days of totals with average and over-limit days; 30 days with Pro.
❤️Apple Health (Pro)
Write dietary caffeine to Health so it sits next to your sleep data. Deleting a drink removes the sample.
🌍19 languages, offline
Nothing leaves the phone. No account, no ads, no analytics.
Questions this app answers
How long does caffeine stay in your system?
Its half-life is about 5 hours for most adults, so a 95 mg cup at 3 PM is roughly 48 mg at 8 PM and 24 mg at 1 AM. The app plots exactly this curve for everything you logged.
When should I stop drinking coffee to sleep?
It depends on your bedtime, your sensitivity and what you already had. With a 50 mg target and an 11 PM bedtime, a single 95 mg coffee has to be in by about 6:20 PM; if you had two earlier cups, much sooner. The curfew card does this calculation continuously.
How much caffeine is in an espresso, a latte or a cold brew?
Typical values: espresso 63 mg, latte or cappuccino 75 mg (one shot), drip coffee 95 mg, cold brew 200 mg, black tea 47 mg, green tea 28 mg, matcha 70 mg, a 250 ml energy drink 80 mg. All presets are editable by size, and Pro lets you enter exact amounts.
How much caffeine per day is too much?
The commonly cited guideline for healthy adults is 400 mg a day; 200 mg during pregnancy. The app keeps a progress bar against the limit you choose.
Does it need internet or an account?
No. Everything runs on the phone. Apple Health is written to only if you enable it in Pro.
Caffeine Tracker: Curfew vs a notes app and subscription caffeine trackers
Counting cups tells you nothing about tonight. Most caffeine apps do compute the level, but charge a monthly subscription for it. This app does the level, the curfew and the history for free, with a one-time Pro for Health sync.
| Caffeine Tracker: Curfew | Notes / memory | Subscription trackers | |
|---|---|---|---|
| Caffeine still active, with decay curve | ✓ | ✗ | ✓ |
| Bedtime curfew for the last drink | ✓ | ✗ | Some |
| Two-tap logging with typical mg | ✓ | ✗ | ✓ |
| Apple Health sync | ✓ Pro (one-time) | ✗ | ✓ Subscription |
| Works offline, no account | ✓ | ✓ | Varies |
| Price | Free, one-time Pro | Free | Monthly or yearly |
常见问题
How accurate is the estimate?
It is an estimate. Caffeine content varies by brew and brand, and half-life varies between people (roughly 3 to 7 hours). Adjust the half-life in Settings if you know you clear caffeine slowly or quickly. This is not medical advice.
What does Pro include?
Apple Health sync (dietary caffeine), 30-day history instead of 7, and custom drinks with exact amounts. It is a single one-time purchase; there is no subscription.
Does it read my Health data?
No. With Pro and the toggle on, it writes caffeine samples to Health and deletes them when you delete a drink. It never reads anything.
Can I log a drink I forgot?
Yes. Open the full drink list and change the time before adding.
What if my bedtime is after midnight?
Set it normally (for example 1:00 AM). A drink logged at 11 PM still counts towards tonight.
Which languages?
English, Spanish, German, French, Italian, Portuguese, Dutch, Polish, Russian, Ukrainian, Turkish, Arabic, Hindi, Indonesian, Vietnamese, Thai, Japanese, Korean and Simplified Chinese.
Is there an Android version?
Not yet. The iPhone app ships first; an Android build is planned and this page will link to Google Play when it is live.
分步指南
更多用于聊天记录导出和语音消息的本地处理应用
Caffeine Tracker: Curfew uses a simple half-life model and average caffeine contents. It is not a medical device and not medical advice; consult a professional about caffeine and your health.