How the estimate works
Storage is the number of pages times the size of each page's text plus its images. Bandwidth is the number of monthly page views times the average page weight. Both numbers are approximations, but they are usually close enough to tell you whether a plan is far too small or hugely oversized.
What it leaves out
- Backups kept on the same account, which can double or triple storage use.
- Email, which is often counted separately.
- Database size, which grows with comments, orders and plugin data.
- Large downloads such as PDFs, videos and software packages.
- Bot traffic, which can easily be a third of all requests.
An example
A blog with 200 posts, four images per post and 20,000 visits a month, where each visit sees 2.5 pages, comes to well under a gigabyte of storage and roughly 15 to 20 GB of transfer per month. That fits comfortably into almost any plan. The risk is usually not the totals; it is the CPU limit on the days when many people arrive at once.
What to do with the numbers
If the estimate is far below a plan's limits, pick on other grounds: support, speed, backups. If it is close to the limits, look at what is large and whether you can reduce it. Images are nearly always the answer. If you serve big files, consider moving them to object storage or a CDN.