Bandwidth is the amount of data that can be transferred at one time.
Data transfer is the actual amount of data transferred.
Think of it this way. If the speed were that of a tunnel, the bigger the tunnel, the more cars could go through it. Then, the data transfer would be the number of cars that can pass through the tunnel in a given period of time, for example, a month.
How does it affect your website?
The less bandwidth you have, the slower your website will take to load, regardless of your visitor’s connection type. Your visitors will have to wait their turn. The less data transfer, the more often your website will become unavailable because it has reached the maximum amount of data that can be transferred.
How much do you need?
First you need to determine what is sufficient for your website to function. You will need to take into account the size of your website and the number of visitors you have in a month. The goal is to ensure that all of these visitors can view your website without any problems.
Expected number of visitors
Average page size (including all text, graphics and other files).
Expected number of page views per visitor
Number of visitors x Average page size X Page views x 30 days = monthly data transfer of your website.
Let’s assume, for example, that your website consists of 5 pages, each containing text and images. The average page size is 30 KB. You expect 50 visitors per day, and each of these visitors will view all 5 pages of your web site.
Your monthly data transfer would be:
50 visitors X 30KB X 5 pages X 30 days
= 225,000 KB or 0.225 GB/month