Less than most people expect
Red Bull’s standard 8.4 fl oz can carries 80 mg of caffeine. Red Bull describes that as about the same as a cup of home-brewed coffee, and USDA’s reference figure for an 8 oz cup of drip coffee, 95 mg, bears it out. A Grande Starbucks Pike Place Roast has roughly four to five times as much (315 to 390 mg).
The larger cans scale with volume: 114 mg in 12 oz, 151 mg in 16 oz and 198 mg in 20 oz, all by Red Bull’s own figures. That works out to about 9.5 to 10 mg per fluid ounce whichever can you pick, so the can size is the whole story.
Against other energy drinks
Red Bull sits at the low end of its category. A 16 oz can of Monster carries 160 mg, close to a 16 oz Red Bull (151 mg). A 12 oz can of Celsius carries 200 mg, nearly twice a 12 oz Red Bull. The FDA gives the typical range for energy drinks as 41 to 246 mg per 12 fl oz, and Red Bull’s 12 oz can sits in the lower half of it.
Limits, and who should skip it
At 80 mg a can, five standard cans reach 400 mg, the daily figure the FDA cites for healthy adults; two 20 oz cans come to 396 mg. None of the sizes crosses the 200 mg that EFSA assessed as a safe single dose for healthy adults, though the 20 oz can comes within 2 mg of it.
Red Bull’s own page says pregnant and nursing women should limit caffeine to 200 mg a day, two and a half standard cans. The FDA notes that medical experts, citing the American Academy of Pediatrics, advise against energy drinks for children and teens.
If you drink Red Bull alongside coffee, count both. A morning Grande latte (150 mg) and two afternoon 12 oz cans (228 mg) come to 378 mg before anything else.