A Hershey’s chocolate bar has 9 milligrams of caffeine. Iced tea has 15 to 20 milligrams. A standard diet Coke or Pepsi and an espresso shot has about 40 milligrams. An 8 ounce can of certain energy drinks have standardly 80 milligrams of caffeine. A standard 8 ounce cup of coffee has about 100 to 200 milligrams of caffeine.