Pepsi One has 55.5 milligrams of caffeine in 12 ounces, edging out Mountain Dew, which has 55 milligrams in a 12-ounce serving. Some other sodas with high amounts of caffeine include Kick Citrus with 54 milligrams of caffeine, Mellow Yellow with 52.8 milligrams and Tab with 46.8 milligrams.
Most other sodas range from about 25 milligrams to 45 milligrams per serving. For instance, Diet Coke has 45.6 milligrams, while Dr. Pepper has 41 milligrams. Coke Classic, on the other hand, has 34 milligrams. A number of sodas do not have any caffeine and include Sprite, A&W Root Beer, 7UP and Mug Root Beer.