Bandwidth requirement for Webinar Event

[balacpt2005]

We are planning to conduct a webinar for our company's rebranding event. We expect over 5000 attendees and 50 interactive panelists.

Please tell us how much internet speed is required to host this webinar session.

[ExpertswhoJohn]

OK, an individual's connection requirements are not dependent on the number of people. That is Zoom's server to worry about. However, you do have to be mindful of where those people are.
If many of the attendees will be on the same company network, then that can be a problem, but they are mostly downloading content so not so big an issue. (like all watching youtube videos)
If many of the panellists will be on the same company network, then that needs looking at closer as they will be uploading their webcam and downloading everyone else.
If you want to experience the impact of one user, then go to Zoom settings in the Zoom app and find statistics when you are connected. You will see what you are sending and receiving.
Hope that makes sense.

[Ray_Harwood]

Welcome to the Zoom Community, @balacpt2005.

@ExpertswhoJohn's answer is pretty good, but I'll add a few of my own thoughts.

He's basically correct in that the bandwidth requirements for the Host of the webinar is not substantially different whether you have a group of 25 or 2,500 in the audience.

What will vary is the incoming bandwidth for your panelists. But the Zoom client does a good job of only requesting the camera video of the people you "want" to see, which is a function of whether you are in Speaker, Gallery, Immersive, or Floating Thumbnail view.  See this Zoom Support document for some additional details on these views:

https://support.zoom.us/hc/en-us/articles/201362323-Adjusting-your-video-layout-during-a-virtual-mee...

Fortunately part of the algorithm takes into account that, as you attempt to see more people, the individual camera video resolutions get incrementally smaller.  Overall the throughput rate will vary, but Zoom will indeed adjust based on a variety of factors, including end-to-end throughput.  Many people complain "my company has a multi-gigbit fiber optic connection", but don't realize, as @ExpertswhoJohn points out, that if there are many people from your organization watching the same webinar on the same network, your organization's bandwidth requirement is increased for each and every viewer... unless you have implemented the relatively new Zoom Mesh network.  See more on the Zoom Mesh eCDN on the Zoom blog here:

https://blog.zoom.us/introducing-zoom-mesh-2/ 

One thing many people don't realize is that Screen Sharing is transmitted at native resolution.  Don't be letting the big company execs share their PowerPoint on their shiny new 4K monitors!  That will more than double the entire incoming bandwidth requirement for each and every attendee, and discourage animations and fancy transitions on PowerPoints and the like.

Consider having your network folks reach out to Zoom for assistance with IP Bandwidth limiting using this approach:

https://support.zoom.us/hc/en-us/articles/4735015890573-Limiting-network-bandwidth 

Good luck with your event!!  Come back here and give us an update, especially with any lessons learned.