The keyword density tool is useful for helping webmasters and SEOs achieve their optimum keyword density for a set of key terms. Seach engine usually checks keyword density, because they do not want keyword too much or too low. Keyword density help search engine to categorize website, and knows what kind of website it is.
Keyword density needs to be balanced correctly. If it is too low, search engine does not consider the keyword as important. If too high,your page might get flagged as “keyword spamming”.
There are a lot of free tool to check keyword density. One of them is http://www.keyworddensity.com/
The best way to check how much is good is to compare your website with your competitor website.
For example, I have http://www.stockpickguide.com and I want to focus on “stock pick” keyword. So I search for “stock pick” at google. I pick one competitor to compare (http://www.hotstockmarket.com) at keyworddensity.com. You can see what are your difference with your competitor.
