inmycup

About

inmycup is a caffeine tracker. It tells you how much caffeine is in your drink, and shows you how much you have left in your body throughout the day. It lets you know if you will fall below the 50 mg threshold (rule of thumb for undisrupted sleep, although this can vary depending on your body's sensitivity to caffeine) at a given bedtime, and the last time before which you can take a desired dose of coffee to be below 50 mg at bedtime.

Sources

Caffeine values come from:

  • Manufacturer nutrition pages (Starbucks, Nespresso, Death Wish, etc.)
  • The USDA FoodData Central database for branded packaged products
  • Caffeine Informer, used under their data license

Every drink page cites its source URL and the date the value was extracted. When two sources disagree, the manufacturer's value is used.

How does the decay math work

Caffeine in the body follows a single-compartment first-order elimination curve [1]. The half-life of caffeine in healthy adults is typically around 5 hours, though it varies from 3 to 7 hours depending on genetics, age, contraceptive use, and other factors [2], [3]. The calculations here use 5 hours by default. The sleep-disruption threshold is 50mg. Above that, sleep architecture is measurably affected [4], [5]. The "sleep cutoff" feature solves backward from your bedtime to find the latest time you can drink a given dose and still be below threshold when you go to bed.

Privacy

No accounts/signup. Your logged drinks live entirely in your browser (localStorage). Nothing is sent to a server. Clearing your browser deletes your logged data.

Not medical advice

This site is for general information. Caffeine sensitivity varies. If you have concerns about your caffeine intake (pregnancy, heart conditions, anxiety, sleep disorders, medication interactions), talk to a healthcare professional.

References

  1. M. R. Nehlig, "Kinetic and dynamic description of caffeine," J. Caffeine Adenosine Res., vol. 8, no. 1, pp. 1–9, Mar. 2018, doi: 10.1089/caff.2017.0011. Available: https://www.liebertpub.com/doi/10.1089/caff.2017.0011
  2. J. Grzegorzewski, F. Bartsch, A. Köller, and M. König, "Pharmacokinetics of caffeine: A systematic analysis of reported data for application in metabolic phenotyping and liver function testing," Front. Pharmacol., vol. 12, art. 752826, Dec. 2021, doi: 10.3389/fphar.2021.752826. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8914174/
  3. X. Liu et al., "Pharmacology of caffeine and its effects on the human body," J. Pharmacol. Sci., vol. 4, 100104, Feb. 2024, doi: 10.1016/j.ejmcr.2024.100104. Available: https://www.sciencedirect.com/science/article/pii/S2772417424000104
  4. C. Drake, T. Roehrs, J. Shambroom, and T. Roth, "Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed," J. Clin. Sleep Med., vol. 9, no. 11, pp. 1195–1200, Nov. 2013, doi: 10.5664/jcsm.3170. Available: https://pmc.ncbi.nlm.nih.gov/articles/PMC3805807/
  5. C. Gardiner et al., "The effect of caffeine on subsequent sleep: A systematic review and meta-analysis," Sleep Med. Rev., vol. 69, art. 101764, Jun. 2023, doi: 10.1016/j.smrv.2023.101764. Available: https://academic.oup.com/sleep/article/48/4/zsae230/7815486