Half-life of Caffeine
Understanding the half-life of caffeine is useful for several reasons; it helps one better manage tolerance, addiction, and accumulation of caffeine in the body. Caffeine is a complex drug and the human body is far more complex, so caffeine will affect everyone differently, but for most people the half-life of caffeine is about 5.7 hours.1 A small cup of black coffee from Starbucks can contain as much as 180 mg of caffeine.2 These two facts imply that after 24 hours and no additional caffeine intake there is still 5.4% of the original dose of caffeine in the user's body. It takes over 42 hours to reduce the caffeine in one's body down to 1% of the original dose. So, if one drinks a cup at 8 am, it will take until 7 pm the next day to reduce the amount of caffeine below 1% of the original dose.
Caffeine's half-life of 5.7 hours means that if one drinks caffeine every day, over time the amount of caffeine in their system will build up. Below there is a graph which you can edit to change the original caffeine dose and add additional doses at different times. There is also a sentence stating the time until the caffeine on the graph is below 2 mg (the amount in decaf black tea).
Caffeine less than 2 mg after: 37 hours (1 day 13 hours)
Caffeine in various drinks and food
| Consumables | Caffeine |
|---|---|
| Black Coffee (Blonde Roast) | 180 mg2 |
| Black Tea | 50 mg3 |
| Cacao Powder | 20 mg per tbsp4 |
| Caffè Latte | 75 mg2 |
| Decaf Black Coffee | 15 mg2 |
| Decaf Black Tea | 2 mg3 |
| Flat White | 130 mg2 |
References
- Statland, B. E., & Demas, T. J. (January 01, 1980). Serum caffeine half-lives. Healthy subjects vs. patients having alcoholic hepatic disease. American Journal of Clinical Pathology, 73, 3, 390-3. LINK.
- Starbucks Coffee Company Beverage Nutrition Information
- FAQs | Twinings Tea
- "Navitas Organics Cacao Powder contains a minimal amount of caffeine: approximately 49mg per 15g (2.5 Tbsp.) serving." (personal communication, December 3, 2018).