There's no single answer to how many class hours are required for an MD degree. The total number of hours varies significantly depending on the medical school. While there's a standard curriculum covering basic sciences, clinical rotations, and electives, the *hours* dedicated to each aren't uniformly tracked across institutions. Furthermore, the definition of a "class hour" can vary—some schools may include lab time, others may not.
Instead of focusing on class hours, it's more accurate to say that an MD degree typically requires four years of full-time study. This includes lectures, labs, clinical rotations, and other required activities. The total time commitment is far more than simply the number of hours spent in lectures.