What is the standard interior door height commonly found in most buildings?

The standard interior door height commonly found in most residential buildings is 6 feet 8 inches. This height has been widely accepted in residential construction because it provides sufficient clearance for most individuals while maintaining an aesthetically pleasing proportion in interior spaces. The use of this height helps ensure that doors can comfortably accommodate the average height of people and common furniture, while also allowing for adequate ventilation and light flow throughout the rooms.

Options suggesting heights of 6 feet 6 inches, 7 feet, or 7 feet 2 inches could be found in specific situations, such as custom designs or different architectural styles, but they are not the standard height. Therefore, when planning new constructions or renovations, 6 feet 8 inches is the conventional choice most contractors adhere to, making it the correct answer.