Why these tools exist
This site grew from a simple observation: most people have no idea how long caffeine stays in their body. We wake tired, blame the night, and never connect it to the 3 pm coffee. These tools make that timing visible — when it wears off, when to stop, and how much you actually had.
They are intentionally simple. No account, no app, no download. Open a page, answer a question, get a number you can act on tonight.
Where the numbers come from
The 5-6 hour caffeine half-life is a widely cited range in clinical literature for healthy adults. The 400 mg daily guideline is a commonly referenced reference point, not a universal rule. Serving values (95 mg for drip coffee, 63 mg for espresso, and so on) are typical averages drawn from major reference sources and public datasets.
We keep sources visible and treat everything as an estimate. Real values shift with genetics, weight, brewing, brands, medication, and pregnancy.
What this site is not
These are general planning tools, not medical advice. They do not diagnose, treat, or replace a doctor. If you have health concerns — heart conditions, anxiety, pregnancy, or persistent sleep problems — talk to a clinician before changing your caffeine routine.
Corrections and feedback are welcome via the footer. This is an independent, ad-supported project.
Quick answers
Which drink has the most caffeine?
Energy drinks and large brewed coffees top the list; a large drip coffee can hold 200-300 mg.
Does tea have less caffeine than coffee?
Usually yes — black tea has about half the caffeine of a similar cup of coffee.
Is decaf caffeine-free?
No, decaf still has a small amount, usually 2-15 mg per cup.
Why do numbers differ online?
Brewing strength, bean type, and brand all change the amount. Treat numbers as ranges.
Does cold brew have more caffeine?
Usually yes per cup, because it is more concentrated than drip coffee.