As with any course at the university, the enrollment size of an online course is determined by the academic department or program. For faculty teaching online for the first time, it is recommended that number of students be smaller than the traditional classroom in order to manage the volume of interaction in the course (especially discussions). This range has been anywhere from 15 - 25 students.
Once a faculty member teaches a course once, enrollment for subsequent online courses should be discussed with the department chairperson or academic program director.