When Should You Stop Drinking Coffee?
Track exactly how long caffeine stays in your system and find your personal caffeine curfew for better sleep.
Caffeine Half-Life Calculator
Enter your last coffee time, amount of caffeine, and your sensitivity. See how much caffeine remains hour by hour.
How Caffeine Half-Life Works
What Is Half-Life?
The half-life of caffeine is the time it takes for your body to eliminate half of the caffeine in your bloodstream. For most healthy adults, this ranges between 4 and 6 hours.
Why It Matters for Sleep
Even if you feel alert, caffeine blocks adenosine receptors in your brain. Residual caffeine can reduce deep sleep, increase nighttime awakenings, and shift your circadian rhythm.
Quarter-Life Rule
Many sleep experts recommend having less than 50 mg of caffeine in your system at bedtime. This tool calculates when you reach that threshold based on your intake and metabolism speed.
Practical Sleep Hygiene Tips for Coffee Lovers
Set a Caffeine Curfew
Use the calculator to find your personal cutoff time and stick to it. For most people, 2 PM is a safe benchmark, but your ideal time may be earlier or later.
Know Your Sources
Caffeine hides in tea, chocolate, soda, energy drinks, and some medications. Track total daily intake, not just coffee cups.
Hydrate and Move
Drinking water and light exercise can help your body metabolize caffeine slightly faster, though they won't dramatically change half-life.
Listen to Your Body
If you consistently wake up tired despite enough hours in bed, experiment with moving your last caffeine dose earlier by 30-minute increments.
Important Disclaimer
This calculator provides estimates based on average caffeine metabolism models. Individual results vary significantly due to genetics, liver health, medications, pregnancy, and smoking status. Always consult a healthcare provider for personalized advice about caffeine and sleep.