Google PageRank or PR for short seems to be misunderstood by so many webmasters and SEO specialists that this part of our SEO tutorial we will try to explain the ins and outs of PageRank without getting too deep into the technical maths behind the PageRank algorithm.

Let’s hope so anyway, not easy to explain PR without dealing with some Maths!

Over the years I’ve wrote several SEO articles on PageRank including: Google PageRank and Page Rank which describes the difference between PR and Page Rank (some webmasters get confused) and PageRank Explained which covers a general overview of what PageRank is.

## What is Google PageRank?

No better place for a description of PR than Google itself, from Google’s PageRank Explained page-

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important.”

Important, high-quality sites receive a higher PageRank, which Google remembers each time it conducts a search. Of course, important pages mean nothing to you if they don’t match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines all aspects of the page’s content (and the content of the pages linking to it) to determine if it’s a good match for your query.

Couldn’t have said it better myself, seriously though it’s clear from the above PageRank is very important to Google, it’s the foundation of their search engines algorithm and so very important to search engine optimization rankings.

PR is created or transferred through links and it’s cumulative, a page with a high PR transfers more PR than a page with low PR making different PR valued links not equal in value from an SEO perspective.

Although 2014 Google SEO has many more ranking factors (Google says over 200) which means the importance of PR must have been devalued over the years: more search engine ranking factors means the older ones like PR must have less importance now. PageRank, which is a measure of a pages backlinks is still important in 2014.

### PageRank Checker

If you haven’t already installed a browser addon that shows Google PageRank, open your favorite browser and go to it’s addon page.

For FireFox it’s the top menu “Tools” >> “Add-ons” (or Ctrl shift A).

Search for PageRank or PR and find a FireFox addon you like that includes PR: there’s a number of free FireFox SEO plugins with PR included, some of the FireFox SEO Toolbars include PageRank and other useful features.

I’m using WebRank SEO ToolBar 4.4.1 which includes PR, Alexa and some other SEO metrics, not sure I’m going to keep it, only shows the domains home page PR not single pages: recently bought the PC I’m on now, so trying new SEO toolbars (there’s no best FireFox SEO toolbar).

For Google Chrome it’s the Customize button (button with three lines on the right) – “Tools” >> “Extensions” : “Get more extensions”.

Search for PageRank or PR and find a Google Chrome addon you like that includes PR, like with Firefox there’s plenty o choice for PR checkers.

SEOQuake for example adds a toolbar with PageRank included, really ugly looking SEO toolbar setup as you can see in the screenshot below:

Alternatively you can search Google for “PageRank Checker” and find loads of free online tools for checking a webpages PR including multiple page PR checkers.

The Google toolbar http://toolbar.google.com (used to be what most SEO’s used) only works with Internet Explorer in 2014, I only use IE to check my Stallion Responsive Theme during development, Microsoft IE worst browser ever!

As you can see there’s plenty of ways to check a webpages PR.

### What Does a Specific PR Represent?

When you view a pages PR it gives a number between 0 (the lowest) and 10 (the highest), PageRank is based on a log scale, probably around base 6 to 8: we don’t know for sure, but it doesn’t really matter if we get it wrong since it’s all relative.

This means each PR point increase takes 6 to 8 times the effort as the last PR increase, this can be represented as a point system that is very helpful when analysing PR transfer especially for reciprocal link exchanges.

**PR Points Table if PR is Base 8**

PR1 = 8 points

PR2 = 64 points

PR3 = 512 points

PR4 = 4096 points

PR5 = 32768 points

PR6 = 262144 points

PR7 = 2097152 points

PR8 = 16777216 points

PR9 = 134217728 points

PR10 = 1073741824 points

As you can see the difference between PR1 and PR2 is not the same as the difference between PR2 and PR3. Higher a pages PageRank goes harder it is to go even higher on the Google toolbar display. It might help to imagine each point is the result of a link either directly or indirectly from other pages.

Note: this isn’t accurate, but it helps to picture the difference between say a PR4 page and a PR7 page, PR4 pages takes 4096 links, PR7 page 2097152 links, that’s 512 times more links or 512 times the effort if all links were equal!

### PageRank Formula

It’s not important that you fully understand the original PageRank formula to use PR to your advantage, but here it is for those who would like the details.

From The Anatomy of a Search Engine authored by the founders of Google **Sergey Brin** and **Lawrence Page** we have the the original PageRank formula-

We assume page A has pages T1…Tn which point to it (i.e., are citations). The parameter d is a damping factor which can be set between 0 and 1. We usually set d to 0.85. There are more details about d in the next section. Also C(A) is defined as the number of links going out of page A. The PageRank of a page A is given as follows:

PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))Note that the PageRanks form a probability distribution over web pages, so the sum of all web pages’ PageRanks will be one.

PageRank or PR(A) can be calculated using a simple iterative algorithm, and corresponds to the principal eigenvector of the normalized link matrix of the web. Also, a PageRank for 26 million web pages can be computed in a few hours on a medium size workstation. There are many other details which are beyond the scope of this paper.

There’s probably been some changes over the years (most likely to irritate those offering SEO Services :-)), but the guts of the PageRank formula is unlikely to change in the near future, so we can safely use it as a jump off point for PR analysis.

### PageRank Prediction Calculator

The formula above is cumbersome to work with in the real world since it involves countless iterations of the calculation to reach a PR value and since we don’t know all the variables for a specific page we can’t accurately predict PR for any page using the original PageRank formula as part of PR calculations!

What we can do though is estimate PR transferred through a link using a simplified PageRank formula, it’s rough and ready, but useful when setting up reciprocal link exchanges, you can predict roughly if a link exchange results in more link benefit to your site or your reciprocal link partners site.

First we simplify the PageRank Formula to only determine PR transferred through a single link by replacing the PR value (PR(A)) with the corresponding value (which we will call PR(pts)) from the PR points table we listed earlier (repeated below). C(A) is from the original formula and represents the number of links from the page in question. For those interested we use 0.85 because it’s generally believed the dampening factor in the original formula (1-d) is 0.85.

PR(pts) * 0.85 / C(A) = PR points transferred through one link

**PR Points Table using Base 8**

PR1 = 8 points

PR2 = 64 points

PR3 = 512 points

PR4 = 4096 points

PR5 = 32768 points

PR6 = 262144 points

PR7 = 2097152 points

PR8 = 16777216 points

PR9 = 134217728 points

PR10 = 1073741824 points

#### Example Reciprocal Link Exchange PR Calculations

We have a PR5 page with 49 links from it, you want to setup a reciprocal link exchange with this webpage which will take the number of links to 50. We look at the PR points table above and see PR5 equates to 32768 PR points, plugging these values into our simplified PR formula-

32768 * 0.85 / 50 = 557 PR points

We compare this figure on the table for the closest match. 557 is closest to 512 PR points or a PR3 **(PR3 = 512 points)**. We can predict a single link from the PR5 page above would likely result in a PR3 page if no other links are involved.

We repeat the PR calculation for your links page. You have a PR5 page with 15 links from it, if you setup this link exchange that’s 16 links, what PR would your link partner receive?

32768 * 0.85 / 16 = 1740 PR points(approx 3 times the PR points you’ll gain)

We compare this figure on the table for the closest match. 1754 is between 512 PR points (PR3) and 4096 PR points (PR4). So a single link from your PR5 page above would likely result in a stronger PR3 page (possibly a low value PR4 page) than your link partners if no other links are involved.

Easiest way to use this information is to compare the end results directly-

Partner Links Page: 32768 * 0.85 / 50 = 557 PR points

Your Links Page: 32768 * 0.85 / 16 = 1740 PR points

Your partner gains 1197 PR points (17540-557) than you do, this is enough to make two more PR3 pages (2*512=1024 is very close to the the extra points).

You then have to ask yourself is this reciprocal link exchange in your best interest from a PR point of view. On the face of it no, but you should look at the page/site you are exchanging links with. Is it a popular site, are you likely to receive click thru visitors etc…? Enough PR points to create a couple of PR3 pages isn’t that much of a big deal, the calculation below is where you should think twice about a link exchange.

85% of the PR of a web page is transferred to the web pages it links to, shared equally between all unique links.

Potential link partners PR7 page with 199 links from it (200 after the exchange).

You have a PR6 links page with 9 links from it (10 after the exchange).

Partner PR7 Links Page: 2097152 * 0.85 / 200 = 8913 PR points (two PR4 pages).

Your PR6 Links Page: 262144 * 0.85 / 10 = 22282 PR points (five PR4 pages).

Even though the link partner has a PR7 page the large number of links from it makes it worth far less than the PR6 link. I wouldn’t make the above reciprocal link exchange if I owned the PR6 page, but would if I owned the PR7.

David Law

19 responses to Google PageRankPageRank Calculator

Thanks so much for taking the trouble to explain the maths behind PR.

while I think (myself included) most webmasters understand the principles, it can get very difficult to calculate the resultant set of link benefit from one backlink.

It’s also important to note that reciprocal links gain more points when within similar niches or industries than two reciprocal links that are completely unrelated.

PR9 BackLinks

Hi SEO Dave

I’m impressed by your math skills.

Do you have a formula for working out how many PR1 backlinks equals a single PR9 link?

Cheers

Peter

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