Bandwidth and data transfer are synonomous. It is referring to the amount of data that can be transferred over the network in a fixed amount of time. It is calculated by the size of your web page. For example, if you have a page totalling 20KB in file size, when a visitor loads that page on their browser, they are receiving 20KB of data. It is the same as saying that you have used 20KB of bandwidth.

To calculate bandwidth, you need to consider
a) the size of your web pages
b) the number of web pages being loaded (pageview)
c) the kind of files you offer your visitors. eg. audio, video files.

Most personal websites have only a small amount of data transfer, as their websites are small in file size and they do not have a lot of visitors. Business and professional sites are larger with more visitors and therefore use more bandwidth. If your site offers a lot of graphics, audio or download files and the daily visitors are huge, you'll need to consider a hosting plan that offers sufficient data transfer.

Using HostingChecker.com as an example. The average file size per web page is below 40KB. If there are 1000 web pages being viewed on a particular day, the total data transfer would be 40MB. Or the bandwidth is 40MB x 30 = 1.2GB per month.

The bandwidth offered by our recommended web hosting services ranging from 40GB (WebsiteSource) to 300GB (PowWeb). Unless you are going to have tons of graphic and/or download files, you do not have to worry that you'll ever exceed the bandwidth limit.

Author
Leo L. - Editor of http://www.hostingchecker.com