Caffeine Half-Life & Sleep Calculator
Calculate remaining caffeine in your system at bedtime to avoid sleep disruption.
Caffeine Half-Life & Sleep Calculator
Calculate remaining caffeine in your system at bedtime to avoid sleep disruption.
Note: Caffeine sensitivity varies widely among individuals. This is based on a standard 5-hour half-life.
How This is Calculated
Caffeine remaining at time T = initial dose × (0.5)^(elapsed hours / half-life). The average caffeine half-life is ~5 hours in healthy adults (range 3–7 hours). More than 100 mg remaining at bedtime is associated with significant sleep disruption per research by Drake et al. (2013).
Disclaimer: This tool provides estimates for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
How to Use This Calculator
Calculate how much caffeine will still be in your system when you try to sleep.
- Step 1: Enter the amount of caffeine consumed (mg).
- Step 2: Enter the time you consumed it.
- Step 3: Enter your target bedtime and click "Calculate Caffeine".
Frequently Asked Questions
For most healthy adults, caffeine has a half-life of about 5 hours. This means 5 hours after drinking 100mg of caffeine, 50mg is still active in your system.
Having more than 20-30mg of active caffeine in your system at bedtime can disrupt deep sleep architecture, even if you fall asleep easily.
