slide 2 of 4. Fall and Spring: The Typical Semesters A typical college semester can be defined as fifteen weeks long, depending on the school. With a typical fifteen-week-long semester, the academic calendar is divided into three semesters. The fall and spring semesters will both be fifteen weeks long and the third semester, summer, will usually be shorter. The summer semester is generally about twelve weeks long. You might find semester lengths vary from school to school, within a range of one to three weeks.