What is the relationship between the high school Carnegie Unit and a college credit?

One high school Carnegie unit is equivalent to 5 semester hours in college. It also means that in order to complete a Carnegie unit of a subject, you may have to take two classes to complete the 5 credit hours needed. For example, to receive credit for a Carnegie unit of English, you would need to take English Composition 1 & 11, which are both 3 semester hours.