Brewed coffee contains more caffeine than Coca-Cola and iced tea. An 8-ounce serving of coffee contains between 80 and 135 milligrams of caffeine.
Coca-Cola contains the least amount of caffeine with 34 milligrams per serving. Eight ounces of brewed ice tea contains 47 milligrams of caffeine.
Many carbonated drinks, including A&W Root Beer, Fresca, Ginger Ale and Sierra Mist, are caffeine-free. Hot beverages like green tea are low in caffeine and contain as little as 10 to 15 milligrams.
Energy drinks have high caffeine content, and one serving averages between 80 and 110 milligrams. Caffeine is also found in foods like chocolate and various flavors of ice cream.