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Caffeine Half-Life Calculator
Calculate caffeine remaining in your system over time based on intake and biological half-life.
Total caffeine consumed (e.g., coffee ~95mg/cup)
Results
Caffeine Remaining87.1 mg remaining
Hours Until Sub-Sleep-Safe Level15.0 hrs until 25mg
What is it?
Models caffeine clearance from the bloodstream over time, accounting for individual metaboliser speed.
How to use
Enter your caffeine dose, how many hours ago you consumed it, and your metaboliser type. The calculator shows remaining caffeine and when it will drop below sleep-safe levels.
Example scenario
Taking 200mg at noon, an average metaboliser will have ~25mg remaining by 10 PM — approximately sleep-safe.
Pro tip
Keep caffeine below 25mg in your system before bed. Caffeine disrupts deep sleep even when you feel fine falling asleep.