Safe daily caffeine limit by body weight
Most sources quote a flat 400 mg per day for healthy adults (FDA). Research often frames tolerability around roughly 3–6 mg per kg of body weight, which is why the same coffee hits a 55 kg and a 95 kg person differently. Enter your weight to see your personal range next to the general guideline.
A common research band is about 3 mg/kg for a moderate daily intake and ~6 mg/kg as an upper bound, shown next to the flat FDA guideline.
Estimates for general information, not medical advice. Pregnant people are usually advised to stay under ~200 mg/day.
How to use it
- 1Enter your body weight and pick kg or lb.
- 2Read your moderate (≈3 mg/kg) and upper (≈6 mg/kg) daily ranges.
- 3Compare them to the flat FDA 400 mg/day limit.
- 4Check your typical drinks against that ceiling.
Why a flat limit is only half the answer
The widely cited ceiling is 400 mg of caffeine per day for healthy adults, the level the FDA describes as not generally linked to negative effects. It is a useful anchor, but it ignores body size. Research on caffeine tolerability often works in milligrams per kilogram: roughly 3 mg/kg is a moderate daily intake and around 5–6 mg/kg is an upper bound before side effects become common. For a 60 kg person that upper band lands near 360 mg, close to the flat limit; for a 90 kg person it is over 500 mg.
What the number does not capture
Weight is one input among several. Genetics control how fast your liver clears caffeine through the CYP1A2 enzyme, so two people of the same weight can react very differently. Pregnancy lengthens caffeine half-life dramatically, which is why the guidance drops to about 200 mg per day. Certain medications, smoking and regular tolerance all shift the line. Treat the weight-based range as a starting estimate, not a personalized medical dose.
Staying under your ceiling
The practical problem is rarely a single drink — it is the total. A morning cold brew (200 mg), an afternoon energy drink (160 mg) and a soda (34 mg) already clear 390 mg before dessert. Logging each drink is the only reliable way to know your running total, which is exactly what the CoffeeLog app does automatically across coffee, tea, energy drinks and soda.
Frequently asked questions
What is the safe daily caffeine limit?
The FDA cites up to 400 mg per day for most healthy adults — about four cups of brewed coffee. Pregnant people are usually advised to stay under about 200 mg per day.
Does body weight change my caffeine limit?
It can. Tolerability is often described as roughly 3–6 mg per kg, so a heavier person may tolerate more in a single dose. Sensitivity, sleep and medication still matter more than weight alone.
Track this automatically with CoffeeLog
Log any drink in one tap, watch caffeine fade in real time on your home screen, and get a nudge before it touches your sleep — the same engine that powers this page.
Related
TrackCaffeine provides general reference information about caffeine. It is not medical advice. Caffeine values are public-source estimates, not exact measurements.