Keyword density is the measurement in percentage, the number of times a keyword or phrase appears compared to the total number of words in a page. In the context of search engine optimization keyword density can be used as a factor in determining whether a web page is relevant to a specified keyword or keyword phrase. Due to the ease of managing keyword density, search engines usually implement other measures of relevancy to prevent unscrupulous webmasters from creating search spam through practices such as keyword stuffing. The formula to calculate your keyword density on a webpage for SEO purposes is : (Nkr / Tkn) * 100 Where Nkr is how many times you repetead a specific keyword and Tkn the total words in the analyzed text. This will result in a keyword density value.
Keyword density is a critical factor in making your site or blog page Google friendly ... a keyword density of at least 3% (maximum 6%, or you will get sandboxed by Google for stuffing keywords). Keyword prominence (your main keywords at the start of your page and the end of your page) is also an important factor when you optimize for Google. The challenge with Keyword Density and Keyword Prominence is always how to create content that is both Google and Reader friendly. A high keyword density and all your keywords in the first paragraph of your page may cause your content to be perceived as unnatural. My advice is to create content that is reader friendly first and then optimize for Google to find the right balance between attractive content for your reader and indexable content for Google. Cheers & More power to you! Aristoteles