Google PageRank Calculation

by Sanju 2010-01-05 21:53:04

Google PageRank Calculation

The Google PageRank (PR) is calculated for every webpage that exists in Google's database. It's real value varies from 0,15 to infinite, but for representation purposes it is converted to a value between 0 and 10 (from low to high). The calculation of the PR for a page is based on the quantity and quality of webpages that contain links to that page.

According to Sergey Brin and Lawrence (Larry) Page, Co-founders of Google, the PR of a webpage is calculated using this formula:

PR(A) = (1 - d) + d * SUM ((PR(I->A)/C(I))


* PR(A) is the PageRank of your page A.
* d is the damping factor, usually set to 0,85.
* PR(I->A) is the PageRank of page I containing a link to page A.
* C(I) is the number of links off page I.
* PR(I->A)/C(I) is a PR-value page A receives from page I.
* SUM (PR(I->A)/C(I)) is the sum of all PR-values page A receives from pages with links to page A..

In other words: The PR of a page is determined by the PR of every page I that has a link to page A. For every page I that points to page A, the PR of page I is devided by the number of links from page I. These values are cumulated and multiplied by 0,85. Finally 0,15 is added to this result, and this number represents the PR of page A.

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