how many milligrams of caffeine is in a cup of coffee?
They have a lot more caffeine than an 8-ounce cup of coffee.. That 8-ounce cup of coffee has about 100 milligrams of caffeine, although coffees and teas vary widely in their caffeine content depending on how they are brewed. For example, CR finds that 8 ounces of Starbucks coffee has 165 milligrams of caffeine. CR says safe limits of caffeine are up to 400 milligrams per day for healthy adults, 200 milligrams a day for pregnant women, and up to 45-85 milligrams per day for children, depending on weight.