The terms bandwidth and data transfer are often used interchangeably by web hosting companies. Although closely related, the two terms do in fact mean different things. Bandwidth is the amount of data that can potentially be transferred at one time, whereas data transfer is how much data is actually being transferred. However, as I said, you’ll find a lot of web hosting companies using the term bandwidth as a measure of how much data you can transfer per month.

The various plans offered by web hosting companies will include some measure of the amount of bandwidth that your site will be able to use. This figure is normally given in gigabytes (Gb) per month, for example a plan may offer 5Gb/month. This means that the total amount of data transfer used by your site for any purpose should not exceed 5 GB.

I must mention here the myth of “unlimited bandwidth”. Some web hosting companies will offer this as a lure to the unwary customer. There is no such thing as unlimited bandwidth. Although some companies may seem to offer this, in practice a careful reading of their terms and conditions will reveal all sorts of rules and restrictions that limit the bandwidth. One such rule may be that “the offer of unlimited bandwidth is subject to acceptable use”, where acceptable use is defined as using less than an arbitrary amount of bandwidth per month. Go over that limit and you may find yourself paying a large surcharge. Or the hosting company may restrict the type of site you offer – no graphics- heavy pages, for example – or the number of pages you may offer on your site. Unless you know for an absolute certainty that you will be able to live with these restrictions not only now but also in the future, then stay away from such plans.

So, how much bandwidth will you need? If you already have a site up and running this should be fairly easy to estimate, based on the reports available from your current web host. If this is a new site then you will need to make some estimates. You will need to know the number of visitors you expect per day, the number of pages you expect each visitor to look at and the average page size. Then multiply all three together, to give you a daily total. Then multiply that figure by 30 to get a monthly total. You will also need to allow for email usage, and for any uploads needed to update and maintain the site. If you plan to offer file downloads then you will need to factor that in too.

Remember that the figure you calculated is the bare minimum needed to keep your site running, and it is only an estimate. You will need to add in a margin for error, and also an allowance for future growth – as your website becomes more popular then your bandwidth usage will increase.

Check the hosting company’s’ terms and conditions to see what will happen if you exceed your allotted bandwidth. There are two things that may happen. Firstly, the host may cut your site off for the remainder of the month, displaying a page stating that “This site has exceeded its bandwidth for the month, please return next month”. This is not what your customers want to see, and will not endear you to them. The other thing that may happen is that you will have to pay surcharges over and above your normal monthly fee. These fees may be many times greater than your normal monthly fee, so although the site is still accessible it is no longer profitable. It is far better to pay a little more per month to keep this from happening, or to choose a web hosting company that will allow you to occasionally exceed your bandwidth allowance for a more reasonable fee.

There are ways of reducing the bandwidth that you use. Make sure that any graphics that are used are optimized for viewing on the Web. Streaming audio or video consume a lot of bandwidth – they may look cool but are they really necessary? Use a single CSS file for all of your pages, instead of embedding the formatting within each page. The same goes for any Java or JavaScript functions used – these should all be called externally too. Clean up all your HTML files, taking out unnecessary comments and spaces. Don’t use too many META tags, keeping only those that are relevant will not only reduce your bandwidth usage but actually is better for search engines.

Once your site is up and running, you will be able to see how good your estimates were. Most web hosting companies will offer detailed traffic reports, showing how many visitors viewed your site, and what pages they viewed. Try to check this regularly – you may find that your estimates were too pessimistic. This will allow you to upgrade before you need to pay any surcharges. Or alternatively you may have been over-optimistic, and your site is only using a fraction of the bandwidth you are paying for. In this case then down-grading your service may save you some money. Don’t cut too much though, remember most web sites become more popular with time, and you may find yourself up against bandwidth limits before you realize.