You can also use this SEO Toolbar for Firefox. Aside from giving you the Google PageRank, it will also tell you a particular page's Alexa and Compete traffic ranks, as well as provide SEO information such as * Backlinks to the domain registered with Yahoo and Google. * Indexing on Yahoo and Google. * Title, Meta Keywords, Meta Description and H1, H2 tags on the page. On top of that you will also be able to * Check the Whois information on the domain. * Read the robots.txt file on the domain. * Check when the domain was created and how old it is. * Check if the domain has an XML sitemap, and look at the contents. And you will have the option to - Choose the position you want this addon to appear in your browser. - Select the Whois Source engine. - Enable and disable the Traffic rank sources.
only way to get an accurate reading is to go to the googleplex and have a look on their computers. For a rough level use the google tool bar. If you are listed in google directory you can see if your are above or below other sites in your category with the same PR if you order the page by PR level.