The pH level of orange juice falls between pH 3.3 and pH 4.19. The varying range of the pH level is due different orange juice formulations having different levels of certain chemicals, which change the overall pH.
The pH level of a solution is a measure of how many available hydrogen ions there are in solution. A solution with a pH number lower than 7 is considered an acid, while one with a pH above 7 is a base. The acidic ingredient in orange juice is known as citric acid. This is found in many citrus fruits such as lemons and limes and gives them the characteristic sour flavor.