Generally speaking, most colleges and universities require students to take a minimum of 12-15 credit hours per semester in order to be considered a full-time student. However, some colleges may require students to take as many as 18-21 credit hours per semester in order to be considered full-time.
Ultimately, the best way to find out how many courses you need to take in college is to contact the admissions office of the college or university you are interested in attending.