An SEO Myth
Optimum Keyword Density
This is another remnant of the past similar to META Tags. On Page factors such as this have very little effect. Keyword density is the amount of keywords on a page expressed as a percentage of the total amount of words on that page.
KD = Keyword Density
KW = Number of Keywords (A phrase of keywords can be considered as one keyword and one word.)
W = Number of Words on page (including keywords)
KD = (100 / W) * KW
So a page with 100 words that has its keyword in the text repeated 4 times has the following Keyword Density.
KD = (100 / W) * KW = (100 / 100) * 4 = 4% Keyword Density
The problem with keyword density is that because you can easily asign a percentage to it everyone suddenly has an opinion on what the optimum value for keyword density is.
Values like 8 - 25% are seomtimes touted as being the "best" keyword density. The only thing I can say to that is try reading something with a keyword density of 25%. It is near unreadable and any bennefit you may have had in the ranking algorithm (how ever small that may be) will be lost because your visitor will jsut click back. I will try to demonstrate this in the next paragrpah.
Keyword density is the density of your keywords within body text. The keyword density of a page requires that your keyowrd, eg keyword density is written lots of times to make your keyword density higher.
That paragraph is 35 words in total although if you count the keyword phrase string as one keyword that makes the
effective number of words for calculation 32. I mention the keyword - "keyword density" 4 times and also have the
seperate keywords from the phrase an in two places. So, lets calculate that rambling keyword stuffed parapgrah that
you probably didn't read.
KD = (100 / W) * KW = (100 / 32) * 4 = 12.5%
So that is a keyword density of 12.5% and it is difficult to read and not a very legible paragraph.
I have also heard someone quote a very exact figure of around 4.28735% as the "optimum keyword denesity". I have absolutely no idea how you could prove that was the optimum keyword density.