How many participants can a BigBlueButton session have?

There is no single fixed number, because the limit depends on the server and on how people use audio and video. What the BigBlueButton documentation says:

• Per server: a server that meets the minimum requirements can handle roughly 200 simultaneous users in total. That could be one class of 200, or several smaller classes (for example 4 × 50 or 8 × 25).
• Per session: the documentation recommends not going above 200 users in a single session.

What changes the real figure:

• Webcams. Video is the heaviest load. If every participant shares a webcam, each person receives many video streams, and both the server and users' devices and connections hit their limits much sooner. A class of 30 with all cameras on can load a server more than a lecture of 150 with only the teacher's camera.
• Server size and bandwidth. More CPU cores and bandwidth help, up to a point.
• Users' devices and connections. Older laptops and weak Wi-Fi struggle with many video tiles.
• Free plans have their own, much lower caps (see the question on the free Moodle service).

For more users in total, organisations run several BigBlueButton servers behind a load balancer called Scalelite, which spreads meetings across servers. This raises total capacity, but a single meeting still runs on one server.

For large audiences that mostly watch, a webinar setup works better: only presenters use camera and microphone, or the session is streamed to a platform built for large audiences.

Practical advice from the documentation: run a test with real users before an important event, and keep webcams off for people who do not need them.