Track Your Caffeine — When Can You Sleep?
Pharmacokinetic model with half-life decay. Energy curve, sleep predictor, FDA limit. Plan your coffee wisely!
✨ The Fun Behind This
Why It's Fun
Caffeine has a half-life of about 5 hours. After 5 hours, half remains. This calculator models your total caffeine load so you can plan when to stop and when you'll be able to sleep.
How It Works
C(t) = C₀ × 0.5^(t/5). Each 5 hours, half remains. Multiple drinks add with their own decay. Sleep threshold: <50mg.
Key Insights
- ●FDA limit: 400mg/day for healthy adults. Pregnant: 200mg.
- ●Stop caffeine 6–8 hours before bed for most people.
- ●Cold brew and energy drinks pack the most caffeine per serving.
- ●CYP1A2 gene affects metabolism—"fast" vs "slow" metabolizers.
Track Your Caffeine — When Can You Sleep?
Pharmacokinetic model with half-life decay. Energy curve, sleep predictor, FDA limit. Plan your coffee wisely!
☕ Click to Load Preset
☕ Current Caffeine Level
Drinks (up to 5)
You
📈 Caffeine Levels Over 24 Hours
📊 Each Drink's Contribution
For educational and informational purposes only. Verify with a qualified professional.
🎲 Fun Facts
Caffeine half-life is 4–6 hours. Genetics and tolerance affect this.
— Pharmacology
A typical drip coffee has 80–200mg depending on size. Espresso ~64mg per shot.
— FDA
Lethal dose is ~150mg/kg. Fatal overdoses from pills/energy drinks have occurred.
— Toxicology
CYP1A2 gene affects caffeine metabolism. "Fast" vs "slow" metabolizers.
— Genetics
Caffeine has a half-life of about 5 hours. After 5 hours, half the caffeine remains. This calculator models your total caffeine load over 24 hours so you can plan when to stop drinking and when you'll be able to sleep.
📋 Key Takeaways
- • FDA limit: 400mg/day for healthy adults
- • Half-life: ~5 hours — stop 6–8 hours before bed
- • Sleep threshold: <50mg for minimal disruption
- • Cold brew & energy drinks pack the most caffeine per serving
💡 Caffeine Facts
📐 Pharmacokinetics of Caffeine
Caffeine follows first-order kinetics: C(t) = C₀ × 0.5^(t/5). Each 5 hours, half remains. So 200mg at 8am → 100mg at 1pm → 50mg at 6pm → 25mg at 11pm. Multiple drinks add together with their own decay curves.
Sensitivity multiplies effective dose: "High" = 1.4× (you feel it more), "Low" = 0.7× (tolerance). Body weight has minor effect; genetics and habit matter more for most people.
🛏️ Sleep and Caffeine
Even small amounts of caffeine can delay sleep onset and reduce deep sleep. The "6-hour rule" (no caffeine 6 hours before bed) is a good guideline. This calculator finds when your level drops below 50mg—a practical "safe to sleep" threshold for most people.
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