We recommend that you have at least 500 KB/sec upstream and 1 MB/sec download bandwidth. The upstream bandwidth is the amount of bandwidth your computer has available to transmit data to the BigBlueButton server. It also depends on your activity; if you are not broadcasting through a webcam, your upstream bandwidth requirements are far less.
A good way to check your bandwidth is at speedtest.net. Your actual bandwidth may be less than your ISP claims, which can be a result of ISP throttling or background activity on your computer.
If you are broadcasting through a webcam or sharing your desktop, we recommend as much upstream bandwidth as possible.