Caffeine Sleep Calculator
Find your ideal caffeine cutoff time based on your metabolism. See how your coffee intake affects your sleep quality.
Calculate Your Caffeine Cutoff
Based on caffeine half-life and your personal metabolism
Save Your Caffeine Plan
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Caffeine metabolism varies significantly between individuals based on genetics, medications, and health conditions. These calculations are estimates based on average half-life data. Consult a healthcare provider for personalized advice, especially if pregnant or have health conditions.
The Science of Caffeine Half-Life
Caffeine has a "half-life" - the time it takes for your body to eliminate half of the caffeine. For most adults, this is about 5 hours, but it can range from 3-7 hours based on various factors.
Our Calculation Method
- Base half-life: We start with the average 5-hour half-life
- Metabolism factors: We adjust based on factors like pregnancy, smoking, age, and medications
- Sensitivity level: Your target bedtime caffeine level (25-75mg) based on sensitivity
- Drink stacking: We calculate cumulative caffeine from multiple drinks
The Formula
Remaining caffeine = Initial dose x 0.5^(hours elapsed / half-life)
For example, 100mg of caffeine with a 5-hour half-life leaves approximately 50mg after 5 hours, 25mg after 10 hours, and so on.
Common Caffeine Sources
| Drink/Food | Serving Size | Caffeine (mg) |
|---|---|---|
| Espresso | 1 shot (30ml) | 63 |
| Drip Coffee | 8 oz (240ml) | 95 |
| Cold Brew | 8 oz (240ml) | 200 |
| Instant Coffee | 8 oz (240ml) | 62 |
| Black Tea | 8 oz (240ml) | 47 |
| Green Tea | 8 oz (240ml) | 28 |
| Matcha | 1 tsp (2g) | 70 |
| Red Bull | 8.4 oz (250ml) | 80 |
| Monster | 16 oz (473ml) | 160 |
| Coca-Cola | 12 oz (355ml) | 34 |
| Dark Chocolate | 1 oz (28g) | 23 |
| Decaf Coffee | 8 oz (240ml) | 2-5 |
Note: Caffeine content can vary significantly based on brand, brewing method, and serving size.
What Slows Down Caffeine Metabolism
- Pregnancy: Half-life can double or triple, especially in the third trimester
- Hormonal birth control: Oral contraceptives can increase half-life by 50%
- Liver conditions: Reduced liver function significantly slows caffeine processing
- Age: Older adults tend to metabolize caffeine more slowly
- CYP1A2 gene variants: "Slow metabolizers" can have half-lives of 8-10+ hours
What Speeds Up Caffeine Metabolism
- Smoking: Induces CYP1A2 enzyme, nearly halving the half-life
- Regular exercise: May slightly increase metabolism rate
- Cruciferous vegetables: Broccoli, cauliflower may boost caffeine clearance
- CYP1A2 gene variants: "Fast metabolizers" may clear caffeine in 2-3 hours
What Makes This Calculator Different
- Multiple metabolism factors: Account for pregnancy, medications, age, and lifestyle
- Drink stacking: Add multiple drinks and see cumulative effects
- Visual decay curve: See your caffeine levels throughout the day
- Sleep impact prediction: Understand how caffeine affects your sleep quality
- Personalized sensitivity: Adjust for your individual caffeine tolerance
About Spacire
Spacire is a UK-based sleep wellness company offering free science-backed tools and curated sleep products. We believe everyone deserves better sleep.
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