Your Website Builder account uses bandwidth when it sends or receives data with the rest of the Internet. For example, if your website contains a 1MB picture, and 2,000 visitors view the picture, it uses 2,000MB (2GB) of bandwidth.
You can check how much bandwidth your account has used, as well as its monthly limit, at any time.
NOTE: If you exceed your account's allotted bandwidth, your account will be automatically upgraded to the bandwidth level needed to handle your extra usage by 5GB, 10GB or 15GB. You will be automatically charged for that extra amount. Your account will remain at that more expensive, higher bandwidth level until you manually reset it to the previous lower level.
If you expect to temporarily need more bandwidth for a month or more, you can prepay to increase it for that period. For more on changing your Website Builder's bandwidth allotment, see Upgrading or downgrading your plan.