Half the daily limit in one can
A standard 12 fl oz can of Celsius carries 200 mg of caffeine, by Celsius’s own figures, and the Celsius Vibe line matches it. That is two and a half standard 8.4 oz cans of Red Bull (80 mg each), a little over two 8 oz cups of drip coffee at USDA’s reference strength (95 mg), and 40 mg more than a 16 oz Monster in a smaller can. Per fluid ounce, Celsius runs about 17 mg, against roughly 10 for Red Bull or Monster.
The rest of the range matches it or goes higher. Celsius Essentials, in a 16 oz can, carries 270 mg. The On-The-Go powder sticks carry 200 mg per packet, the same as a can. Celsius Hydration powders contain no caffeine.
What Celsius itself recommends
Celsius’s own FAQ recommends no more than two 12 oz cans a day, and points out that two cans are 400 mg, the daily figure the FDA cites for healthy adults. It also recommends that people new to energy drinks have no more than one Celsius product in 24 hours, and that even people with a high caffeine tolerance keep to two cans, or one Essentials, a day.
Two cans leave no room for anything else. A morning cup of drip coffee on top of them takes the day to 495 mg, and an Essentials with a Grande Caffè Latte comes to 420 mg.
The single-dose line
EFSA assessed single doses up to 200 mg as not raising safety concerns for healthy adults. A can of Celsius sits exactly on that line, and a can of Essentials is 70 mg over it, so neither is one to finish quickly on top of other caffeine.
In pregnancy, one standard can is the whole of the 200 mg daily ceiling ACOG uses. The FDA notes that medical experts, citing the American Academy of Pediatrics, advise against energy drinks for children and teens.