Understanding The Basics of PageRank
PageRank: The Short Explanation
Your web pages PageRank is determined by only three factors:
1. The number of pages linking to your page.
2. The PageRank of the pages linking to your page.
3. The total number of outgoing links from the pages linking to your web page.
You gain the greatest PageRank boost from pages that a) themselves have high PageRank and b) link to only a few other websites. Even incoming links from pages of low PageRank with many outbound links will boost your pages PageRank–as long as you don’t link back to them.
That is, as far as PageRank is concerned, every unreturned incoming link is a good link.
The tricky part in the equation comes into play when you begin exchanging links. Because your link to their site affects their PageRank and their link to your site affects your PageRank, things become more complicated.
If you are worried about PageRank, the general rule of thumb is always to exchange links with websites of equal or higher PageRank. Learn more about Exchanging Links with PageRank in mind.
It’s important to remember, PageRank isn’t everything. There are lots of other reasons to exchange links with websites. For example, when you think it’s a good website. PageRank is only a very small factor in Googles overall search engine ranking equation.
The PageRank Calculation
As published in the original paper as published by Sergey Brin and Lawrence Page:
PageRank of Your Page = .15 + .85(PR(T1)/C(T1) + PR(T2)/C(T2) + … + PR(Tn)/C(Tn))
T1 through Tn are pages providing incoming links to Your Page
PR(Tn) is the PageRank of Tn
C(Tn) is total number of outgoing links on Tn
Google ToolBar PageRank
It is important to note that the true PageRank as determined by this formula is not the same as the PageRank displayed by the Google Toolbar. True PageRank can range from .15 to several million. The Google Toolbar displays a PageRank from 0 to 10.
Therefore, each number in the Toolbar PageRank actually represents a range of True PageRank values.
It is fairly easy to gain or loose PageRank at the lower numbers on the Toolbar. However, to go from a Toolbar rank of 9 to a Toolbar rank of 10 is very, very difficult. As an estimate, it would take somewhat over 9 million dedicated PR 1 backlinks to raise a pages PageRank from a low 9 to a low 10.
Based on Log Base 5 Scale
|Toolbar PageRank||True PageRank|
The above is an estimate only based on the assumption that the highest true PageRank currently existing for any page on the Web is almost 49 million. These values actually change every time a new page is added to the Internet. Every time Google indexes a page, the PageRank of every page is recalculated so that the average PageRank of all pages on the Internet is equal to one. Therefore, the true values of the above chart are constantly in flux.
PageRank Calculation Simple Example
Let us assume that your page has 4 pages linking to it as follows:
- Page 1: True PageRank 110, Total Outgoing Links 5
- Page 2: True PageRank 1000, Total Outgoing Links 45
- Page 3: True PageRank 2000, Total Outgoing Links 100
- Page 4: True PageRank 100, Total Outgoing Links 1
Here is how the formula looks when we plug in the numbers:
- PageRank of Your Page = .15 + .85 (PR(T1)/C(T1) + PR(T2)/C(T2) + … + PR(Tn)/C(Tn))
- PageRank of Your Page = .15 + .85 (110/5 + 1000/45 + 2000/100 + 100/1)
- PageRank of Your Page = .15 + .85 (22 + 22.22 + 20 + 100)
- PageRank of Your Page = 121.37
- Estimated Toolbar Rank = 2
We can see here that, in this case, the page with the lowest True PageRank has actually boosted your PageRank the most. Because you were his only outgoing link, Google has allotted your page the full “vote” from this website. On the other hand, in this example, the page with the highest True PageRank boosted your websites PageRank the least because he has spread his voting power over 100 outgoing links.
Now lets see what happens to the numbers if we replace Page 3 with another page of True PageRank 2000 but only 3 outgoing links:
- PageRank of Your Page = .15 + .85 (110/5 + 1000/45 + 2000/3 + 100/1)
- PageRank of Your Page = .15 + .85 (22 + 22.22 + 666.66 + 100)
- PageRank of Your Page = 689.39
- Estimated Toolbar Rank = 4
Obviously, it is nice to attract links from high PageRank websites, but it’s even better if you can be one of their only outgoing links.
Part 2: How To Calculate PageRank