how much caffeine should an adult have
Cup of coffee. If you thought Red Bull was bad, you might be surprised about how much caffeine is really in your favourite drinks. The amount of caffeine the healthy adult should consume a day is up to 400mg and the normal amount in 12-ounce coffee cups contains 90 to 120mg. But one 12-ounce 'tall' or small cup of Starbucks actually has as much as 260mg of caffeine per cup, Business Insider reports.