How bandwidth is calculated?

Summary : Bandwidth is calculated on file sizes. Whether you're uploading or downloading files, you are using bandwidth. This article explains and helps you understand what bandwidth really is.

The term Bandwidth refers to how much data is sent and retrieved from one source to another through the internet. Bandwidth is a term commonly used by both Internet Service Providers
, and Website Hosting Providers
to track and limit the data that is transferred using their services.

For this article I will use the example of a website hosting provider. Most websites are limited to a specific amount of total bandwidth that is allowed to be transferred per month. Every file on your website has a specific file size.

Let's say you have a webpage with a file size of 12kb and you have 3 images on that page, each of which have a file size of 20kb (3 x 20kb = 60kb). Let's also say that you have a midi sound file, that plays automatically on your page which has a file size of 28kb; that is a total of 100kb transferred to your visitor's browser when they load your page.

When that 100kb page is loaded 10 times into a visitor's browser, 1,000kb (10 x 100kb = 1,000kb) or 1MB of bandwidth will be used up. Every file that is transferred contributes to your bandwidth usage.

Many providers will also include the amount of bandwidth used to transfer files to and from your site via FTP or a file management system into your total bandwidth calculation. While making changes to a website often will not cause a huge increase in your bandwidth, if you are constantly changing large files on your site such as music, movies, or software downloads, this may significantly start to increase your used bandwidth.

Images, movies, music and software files are the largest contributors to your bandwidth usage on a website. You should try to limit the use of these types of files whenever possible. Also try to compress images and files to the smallest possible size.

Bandwidth prices have been gradually dropping over the last few years, but while they are dropping, the average file size is increasing. This is causing a see-saw effect. The good news is if you optimize your graphics and compress your files, you can save your self hundreds, or even thousands of dollars as these prices drop.