5-6
625 – 3,125
6-7
3,125 – 15,625
10,000 – 100,000 100,000 – 1,000,000
7-8
15,625 – 78,125
1,000,000 – 10,000,000
8-9
78,125 – 390,625
10,000,000 – 100,000,000
9 - 10
390,625 +
100,000,000 +
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.
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.