Toolbar PageRank vs. Actual PageRank

So how does one find out what the PageRank (PR) value is for a given page? Well, Google has a tool, called the Google Toolbar, which allows you to see a crude approximation of PageRank value. Download and install the free Google Toolbar at

http://toolbar.google.com/

Once installed, it should look like this in your browser:

What most people fail to realize is that the PageRank values shown in the Google Toolbar are not the actual PageRank values that Google uses to rank web pages. The Google Toolbar is divided up into 10 equal linear ranges from 0 - 10. These linear divisions correspond to a logarithmic scale that Google uses. The actual scale is estimated to be anywhere from log base 5 to log base 10. This public Toolbar PageRank is however what people talk and agonize about.

The Toolbar PageRank value only indicates that a page is in a certain range of the overall scale. One PR=5 page could be just above the PR=5 division and another PR=5 page could be just below the PR=6 division, which is a really vast gulf between them.

Although the exact logarithmic base used for PageRank is a secret, the following table should give you an idea of how different the Toolbar PR is from the actual PR.

What this means is that moving a page from a PageRank of 6 to a PageRank of 7 is much harder than moving from a PageRank of 4 to a PageRank of 5.

New pages that the Toolbar displays a PR value for may not have been indexed yet, and as such don't have any “real” PageRank of their own. What is happening is that one page on such a site may have already been indexed and as such PageRank has been estimated for the new page as a result. The new page generally has a PR value 1 point below an indexed page on the site, but this is just an “estimate” PageRank that exists only in the Toolbar. Before exchanging links, search for the actual page on Google to make sure that it is indexed.

Note: PR as viewed using the Toolbar can be pretty inaccurate. Please keep this in mind. During the spring and summer months of 2003, some home pages for sites suddenly showed a PR = 0 (no green bar) when indeed the page did have a PR value. Simply appending /index.html to the URL (or whatever the filename is for the home page) into your browser restored the proper value in the Toolbar. So make sure that the site that you reject exchanging links with truly does not have a PR value.

Whichever scale Google uses, keep in mind that a link from another site increases your site's total PageRank, as explained next. Although PageRank is assigned per page, your site is a collection of web pages under a single domain that you control and hence can be thought as having a total “PR” value too.