Caffeine timing is personal.
Generic advice — “stop six hours before bed” — is wrong for most people. Caffeine & Sleep exists to give you your number, backed by real pharmacokinetics, not a rule of thumb.
Why we built this
Caffeine’s half-life varies three- to nine-fold between people. That means the same afternoon coffee is harmless for one person and a sleep-wrecker for another. Almost every “caffeine calculator” online ignores this — they assume one average half-life, get multi-drink math wrong, and bury the answer under ads.
We started with the app: a tool that tracks your caffeine live, learns your personal clearance rate, and warns you before a late drink costs you sleep. This site is the open, free front door to that same engine.
Vadim Semenko
Built the caffeine half-life engine behind the app and this calculator — the first-order superposition model that powers every number on the site. Writes and reviews all guides for accuracy against primary research.
How we source our data
Every caffeine figure traces to a primary source, in this order of preference:
- Manufacturer labels & spec sheets for branded drinks (Celsius, Monster, Red Bull, etc.).
- USDA FoodData Central for generic coffee, tea and brewed beverages.
- FDA and EFSA guidance for safe-intake thresholds (the 400 mg/day adult ceiling).
- Peer-reviewed pharmacokinetics (e.g. Drake 2013) for half-life and sleep-impact modeling.
Numbers are reviewed on a rolling basis. See our editorial policy for how we write, cite and correct.
Contact
Questions, corrections or press: [email protected].