Web hosting providers often talk about bandwidth and data transfer without explaining that these are two distinct but closely related concepts. Bandwidth refers to the amount of data that can be transferred at the same time; data transfer refers to the total amount of data actually transferred. Think of it this way: if bandwidth were a tunnel, increasing bandwidth means more vehicles can pass through simultaneously. Data transfer is the number of vehicles allowed to cross the tunnel in a month. In short, data transfer represents your bandwidth consumption.

How This Affects Your Website

The lower the bandwidth allocated to your site, the slower it will load — regardless of the visitor's connection speed. If you have too many visitors, some will be forced to wait their turn.

As for data transfer, your website will become unavailable once the volume of transferred data exceeds the allowed limit.

Determining Your Needs

When a hosting provider talks about bandwidth, they are usually referring to data transfer. You need to determine what is sufficient for your site to run properly. Most of this data is available from your traffic history. If you do not have an existing site, provide an optimistic estimate if you plan to promote the site heavily.

Taking the following variables into account:
- Number of visitors / expected visitors
- Page size, including page graphics
- Pages viewed / expected pages viewed per visitor

You can use the following formula:
Visitors × Page size × Pages viewed × 30 days = Monthly website data transfer

You should also add a small margin to account for email traffic and your own uploads to the server.

Unlimited Plans

Bandwidth is relatively expensive. Hosting providers are limited by their own infrastructure. Going back to the tunnel analogy: each visitor to your site is assigned a lane to transfer data. The more visitors you have, the narrower each lane becomes, forcing every visitor to wait longer for the page to load. Most of the time, you have little control over your bandwidth since your host manages it. Some hosts may also limit the number of simultaneous connections, which slows down your site and turns away visitors. Always ask your host about how they manage bandwidth.

Reducing Data Transfer

You can reduce your data transfer usage by building leaner websites and optimizing your graphics. Minify your CSS and JavaScript files using dedicated compression tools. Use image compression software to reduce file sizes. Keep your meta tags to a minimum — too many keywords are not search engine friendly, and most engines will only scan the first few and ignore the rest. Enable mod_gzip on Apache — it can save up to 40% of your bandwidth. Bots can also consume your bandwidth at an enormous rate; use robots.txt to block them.