Some web hosts will offer “unlimited bandwidth." Sounds great, but if you understand shared hosting, you'll know it is impossible for a web host to supply “unlimited” anything. Unlimited bandwidth is more or less a marketing ploy based on the assumption that no user will come close to exceeding bandwidth allotments. However, hosts may still have fines or fees for using too much, "unlimited" or not, so make sure you ask your web host how they define unlimited if this is their offer.

What is bandwidth?
Because you share a server with many other web sites your web host must keep track of how much disk space and bandwidth your site uses. Bandwidth is basically the amount of traffic and content that will be requested from the web hosts server for a set period of time. When a visitor requests a page (ie. types in your domain name into the web browser) the server is contacted and will return your site along with all the graphics and text. The more traffic (requests for your website) you will have the more bandwidth you will need.

How much bandwidth will I need?
As with disk space, if you exceed your allotment for bandwidth your host can charge you a hefty fee. So it is important to know how much you need. Here is the formula for determining the approximate amount of monthly bandwidth your site will need.

Number of pages x .05MB x Number of visitors/month= Total Bandwidth/month

This formula is based on each visitor viewing each page in your site once. Obviously this won’t always be the case. Some visitors may only look at ¼ of your site, while others will scour each page twice. It all averages out in the end.