Bandwidth is the amount of traffic allocated to a website. It is also called data transfer. As users visit and leave your website, they create traffic. This traffic represents wear and tear on the web host equipment so they charge website users accordingly. The more traffic you have for your website, the more bandwidth you will need. Sites that offer heavy applications such as chat, forum, software download and video uploads and download would have to get very high bandwidth.
As you may see from Figure 1, higher bandwidth makes a site more versatile and therefore costs more.
* Figure 1. A web host chart showing bandwidth prices
You web host must be able to provide you with a high bandwidth if you are going to incur very heavy traffic at your website. You will not want to visit your site one day to see a Bandwidth Exceeded notice.
To calculate your bandwidth, you will have to make a projection of what services you will offer and how many people would visit your site in a day or month. If you forecast 100,000 visitors a month and each visitor browses 10 pages of about 60K size, then your bandwidth needed would be 100,000X10X60K=60,000,000 or 60GB.
So by this simple calculation, you realize that you need a bandwidth of 60GB.
The web host you choose must therefore offer you this amount of data traffic. If you have a simple website with only text and graphics, then 40GB would be just enough.
As you look for hosts, be careful not to be confused about the Unlimited Bandwidth offer used on many web host sites. This offer is different from actual bought bandwidth. The unlimited bandwidth offer is mostly used for small, shared hosting websites and it is usually unpaid for. The assumption is that small sites do not consume much bandwidth and would never exceed 40 GB bandwidth or thereabout, no matter what traffic they experience. If you anticipate heavy traffic, buy the required bandwidth as the unlimited bandwidth offer is not guaranteed.
If you have a small site but anticipate future growth, you should go for a hosting plan that allows you to upgrade to a higher bandwidth service.
Bandwidth is very important in website management. It is essential that you buy the right amount to keep your site running at all times.