Caffeine Half-Life Tracker

JAMGSOFT

About this app

Ever wonder why you can't fall asleep even though you had your last coffee "hours ago"? Caffeine doesn't just disappear — it takes roughly 5 hours for your body to eliminate just half of it.

Caffeine Half-Life Tracker shows you exactly how much caffeine is still active in your system right now, and precisely when it will drop low enough for quality sleep.

How it works
Log your drinks as you go — coffee, tea, energy drinks, or anything custom. The app models how caffeine is absorbed over about 40 minutes, then uses your body's half-life (approximately 5 hours) to draw a real-time curve and tell you when you'll be in the clear.

Features
• One-tap logging for espresso, drip coffee, lattes, cold brew, green tea, black tea, matcha, chai, yerba mate, Red Bull, Monster, Diet Coke, pre-workout, and more
• Your usual drinks become quick chips on the home screen, the home-screen widget and app-icon shortcuts
• Real-time mg counter with color-coded status (red → green as caffeine clears)
• Forecast graph showing your caffeine curve, its peak, and the next 12 hours
• Sleep-ready countdown — know exactly when it's safe to wind down
• Caffeine budget — see how much more fits today and still lets you sleep on time, with what-if previews before you log
• Sleep insights — rate your sleep each morning (right from the notification) and see how caffeine at bedtime affects your nights; the app suggests a personal sleep threshold from your own data
• Daily limit — set your own cap and get a heads-up when a drink would go over
• Home-screen widget with your live level, sleep-ready time and one-tap logging
• Edit or back-date any entry; half, double and triple servings; instant undo
• Reverse calculator — how much can you still drink to hit a target level later?
• Custom drink support — add any drink with your own mg amount
• Sleep reminder notification when your caffeine drops below your personal threshold
• Adjustable half-life (2–12h) to match your own metabolism
• Fully offline. No account. No ads. No tracking.

Who it's for
Coffee lovers who want to time their last cup smarter. People who struggle with sleep but haven't connected it to caffeine. Anyone who's ever had a 2 AM heart race and wondered why.

Stop guessing. Start sleeping.

What’s new

What's new in 1.3.0
• Sleep insights: rate your sleep each morning (right from the notification) and see how caffeine at bedtime affects your nights
• Caffeine budget: see how much more fits today and still lets you sleep on time
• Set your own daily limit, with a heads-up when a drink goes over
• Smarter forecasts: caffeine now ramps up over ~40 min, with its peak shown
• Log your usual drinks straight from the home-screen widget
• Clearer graph labels and other fixes