Zoom Quality and Data Usage

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Zoom is the video conferencing tool that NC State Extension uses. On top of using Zoom for meetings with co-workers, we’re now using it to hold online classes and training with our clientele. Because of this, there’s one question that has come up more than any – “How do we get the best experience with Zoom?”

Zoom quality depends on the client’s internet access to work. The reality in North Carolina, in March of 2020, is that broadband access is still not accessible everywhere. A large portion of North Carolina does not have access to broadband service or has not connected to it, though the lack of broadband is more common in rural areas.

Broadband service is defined as an internet connection with a 25mb/sec download speed and a 3mb/sec upload speed. Some rural areas may be served via older DSL or cellular internet where the speeds can be much, much slower.

Zoom meetings can take up a good amount of available bandwidth. Examples pulled from meetings are in the table below.

Meeting Type Down Up
1 to 1 with both participating in video .8 to 1.2 mb/sec .8 to 1.2 mb/sec
1 to 1 with one side doing video (video side) .07 to .1 mb/sec .8 to 1.2 mb/sec
1 to 1 with one side doing video (audio only side) .8 to 1.2 mb/sec .07 to .1 mb/sec
Multi-person (15) meeting with video on all sides 2 to 3 mb/sec .9 to 1.5 mb/sec
Multi-person (15) meeting (person not sending video) 2 to 3 mb/sec .15 to .3 mb/sec
Multi-person (100+) meeting (no video or audio uploading) .15 to .4 mb/sec .01 to .05 mb/sec

Things to take away from the table:

  • If the client does not need to use their video camera or microphone, encourage them to turn it off to save bandwidth.
  • Multi-person meetings do use more bandwidth, but the usage per extra person in the meeting is very low.
  • Check your bandwidth before you host a meeting with video. Speed Test is a simple site to use for this purpose.
    • If you know your bandwidth is higher than what the test shows, then try moving to a new location for better a wireless signal and ask others sharing your internet to refrain from streaming content (Netflix, Youtube) while the meeting is going on.

Most issues with Zoom quality are from the fact that the upload side of most internet connections is much smaller than the download side. For every ten packets of data that comes down, one packet of data is sent up to acknowledge receipt of the ten packets. When the data packet is not sent up, the server will then try and resend the ten previous packets. This is why turning off the video camera is important – you will not know that your upload has filled the available bandwidth. You will experience download issues because of a full upload connection, even if you have plenty of download bandwidth available. The download issues will not only affect your Zoom session but everyone at your location using the internet.

Zoom does make statistics available to you during a session. These stats can be helpful if you are experiencing issues. Zoom will turn the stats’ blocks orange, then red, if there are issues detected.

Zoom has information about the statistics and what they mean on the Meeting and phone statistics page in the Help Center.

More information on Zoom can be found on our Video Conferencing with Zoom blog post.