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Need help with Caffeine Easy?
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Frequently Asked Questions
How does caffeine half-life work?
Caffeine has an average half-life of about 5.7 hours. This means that every 5.7 hours, your body metabolizes half of the caffeine in your system. For example, if you drink a 100mg coffee at noon, you'll have about 50mg at 5:42 PM, 25mg at 11:24 PM, and so on until it's effectively cleared.
What does "Clear By" mean?
The "Clear By" time shows when your caffeine level will drop below 20mg — the point at which caffeine is effectively out of your system and unlikely to affect your sleep. This helps you plan your last coffee of the day.
Is the half-life the same for everyone?
The 5.7-hour half-life is an average. Individual metabolism varies based on genetics, liver function, medications, pregnancy, smoking status, and other factors. Your personal half-life could be anywhere from 3 to 7+ hours. The app provides a good general estimate.
How accurate are the preset caffeine amounts?
Caffeine content varies widely by preparation method, bean type, and serving size. Our presets use industry-standard averages: ~95mg for an 8oz brewed coffee, ~63mg for espresso, ~47mg for black tea, etc. For precise tracking, use the custom entry feature.
Does Caffeine Easy read my health data?
No. Caffeine Easy only writes caffeine intake data (dietaryCaffeine) to HealthKit if you grant permission. It does not read any health data from Apple Health.
Why does my caffeine level show high in the morning?
If you drank caffeine late in the day, some may still be in your system the next morning. Caffeine takes roughly 5-6 half-lives (~30 hours) to fully clear. A late-night coffee can definitely linger into the next day.
Can I edit or delete logged entries?
Yes! Tap any entry in your history to edit the amount or time, or swipe to delete it. Your caffeine level will recalculate automatically.
Does the widget update in real-time?
iOS widgets refresh periodically (not continuously) to save battery. The widget updates frequently enough to show accurate clear-by times, but for real-time visualization, open the app.