So what is keyword density anyway?
Simply put, keyword density is the ratio of keywords or key phrases to the total number of words on a particular page of your site. A good rule of thumb is to have a keyword density of 1-3%. Some may be thinking, "How do you get the keyword density percentage?" The mathematical formula is quite simple: you divide the total number of keywords or keyword phrases in your content by the total number of words.
So if you have 10 keywords in a document with 1000 total words, that's a keyword density of exactly 1%, which is the lowest keyword density your page should have for search engine purposes, anything less and chances are, your site won't be listed high in a search engine. To achieve the ideal keyword density of 3%, you would have to have 30 keywords or keyword phrases in a site with 1000 words. Generally speaking, you don't want to have more than 3% keyword density, as the keywords tend to get repetitive in that case and actually hinder your site. But you also don't want to have less than 1%, as your site won't be noticed as quickly or as effectively by search engines.