The pH or acid level of Coca Cola Classic is 2.5. For perspective, pure water is neutral at a pH of 7. Pure hydrochloric acid is extreme at a pH of 0. At the other end is at a pH of 14. You stomach is too acidic for all but the hardiest of living things to survive at a pH of 1.8-2. The higher the pH the more alkaline or basic. The lower the pH the more acidic. So, yes Coca-Cola is acidic, but not as acidic as the contents of your stomach. The acid in Coca Cola is not bad for your teeth in small amounts, but the sugar is. Be sure to brush often as the bacteria in your mouth have sugar and produce acids that are stronger than Coke, and stick to your teeth, that will cause cavities. If you drink a lot of acidic beverages (soda, lemonade, wine, V8, vinegar etc) it can cause irreversible damage to the protective enamel coating on your teeth, making your teeth more vulnerable to cavities and more sensitive to pain. To minimize acid damage, drink less acidic drinks, use a straw when drinking, or drink water / eat food after or with acidic drinks.