Credit hours are a way of numerically representing all work completed. They are not the same as the actual ‘classroom contact’ i.e. instructional hours. Most institutions of higher education in the U.S. operate on an academic year divided into two equal semesters of 15-16 weeks’ duration, with a winter break of 2-3 weeks and a summer session of 10-12 weeks, plus additional shorter breaks. The actual amount of academic work that goes into a single semester credit hour is often calculated as follows:

• One lecture (taught) or seminar (discussion) credit hour represents 1 hour per week of scheduled class/seminar time and 2 hours of student preparation time. Most lecture and seminar courses are awarded 3 credit hours. Over an entire semester, this formula represents at least 45 hours of class time and 90 hours of student preparation.
• One laboratory credit hour represents 1 hour per week of lecture or discussion time plus 1-2 hours per week of scheduled supervised or independent laboratory work, and 2 hours of student preparation time. Most laboratory courses are awarded up to 4 credit hours. This calculation represents at least 45 hours of class time, between 45 and 90 hours of laboratory time, and 90 hours of student preparation per semester.

A master’s degree program requiring at least 33 credit hours and including a research thesis or project represents over 4,000 actual hours of supervised and unsupervised (independent research) study, while a doctoral program can represent 8,000 or more actual hours of advanced study and research beyond the master’s degree.