* Topic: A highly specialized seminar might attract only a handful of students or researchers. A popular or broadly relevant topic could draw a much larger crowd.
* University size and reputation: Larger universities and those with renowned programs might have larger seminar attendance.
* Professor/Speaker: A well-known or highly regarded professor will likely attract a bigger audience.
* Room size and capacity: The physical space available will limit attendance.
* Type of seminar: A departmental seminar might have a smaller audience than a university-wide lecture series event.
Therefore, there's no single answer. You could see anywhere from a few people (5-10) to several hundred. A typical range for a moderately sized seminar might be 20-50 attendees. Anything above 100 would likely be considered a larger lecture or presentation rather than a seminar.