I set about trying 5 analyzer's on 5 different pages ranked from position 1 to 30 on Google.com. I wanted to see how important keyword density was to ranking order and find the right figure.Of course, if you want to measure keyword density I'm assuming you have already chosen keywords or to be more precise, keyphrases for your web pages. Most single keywords have far to much competition from other web sites using the same words. This is why, these days, you should target keyphrases which comprise 2, 3, or 4 keywords in a sentence or phrase. Keyword Discovery
A precise process for finding the right keywords to get you Search Engine (SE) traffic from targeted visitors interested in what you have to offer. More details can be found at :
Keyword Discovery - Maximize Traffic to Your Web Site
Keyword Density
If you don't know what keyword density is, it's the number of keyword's divided by the word count on the page expressed as a percentage. So, 20 keyword's on a page with a total word count of 500 should be 20 divided by 500 or a keyword density of 4%. As we'll see, it's not quite so simple. A keyword density of between 2% to 20% for a page is often quoted as a target figure. Personally I think at 20% you would be regarded by the search engine as spamming ( too much repetition ) for which you could find your site penalized. It would also not make very interesting reading. It might seem obvious to say, but there are only two ways to get higher keyword density. One is more frequent use of the keyword or phrase, the other is having fewer words. It's only when using an analyzer to look at keyword density, you start to realize how difficult & time consuming it can be to reach keyword density figures of 4 to 5% never mind anything higher. Reducing the words on a page often seems like the easier answer to improving density.
Some optimizer's believe that some search engine's look at word count as well as keyword density. It then adds a weighting factor against a page with a low count, compared to say another page with the same keyword density but a higher word count. But is this true, or just a theory and what's an acceptable word count ? Web Position Gold is a respected analyzer that many optimizer's use. For Google.com it recommends a total word count of 505 to 795 with 436 to 629 words in the body text. I carried out an experiment on Google.com running a query on the exact phrase "keyword density" and then used GR Software's GRKda keyword density analyzer to determine the keyword density & word count for chosen pages in the Google rankings. Each page was stored to the hard drive to ensure the software keyword density analyzer checked the same page each time. For the exact phrase "keyword density" there were 55,100 other competing pages on Google. Keyword Density on the total page  In the keyword density column the 1st figure is for "keyword" and in brackets for "density". Only position 30 complies with the analyzer Web Position Gold's recommended total word count ! From the GRKda keyword density analyzer results it's clear the No.1 position is not being significantly penalized for only having a word count of 161 and neither is No.10 with 102 words when compared to the others. Interestingly the No.10 & 19 positions have almost identical keyword density, still with low word count, but the one with lower count gets the higher ranking. This article on keyword density analyzer's continues at:Keyword Density - Getting the Right Result - Pt 2 | 
