I have a doupt on keyword density calculation by google. It will calculate body content or meta tag, body content and title tag?
I am fairly certain that Google looks for density within the body tags, not your metas or titles. Title and meta have a technical purpose, not a content purpose. Google uses them appropriately when considering SERP, not figuring them into keyword density for your content.
Total content on your page, not just the body of the page. Keyword density isn't that important anymore anyway, as long as you don't go crazy with it. If you're at 5% density, you're spammy.
I came back to this thread today and realized that I did a poor job of explaining my opinions of Keyword Density, what is calculated when considering it, and how Google takes it into consideration. Many big names in the SEO world actually believe that Google does not calculate Keyword Density, at least not directly. When G crawls your site, their algorithm is analyzing many different things. These SEO guys believe that G calculates keyword density as sort of an afterthought, something that occurs as a result of some of its other processes. Keyword density is useful in helping a site owner make sure they aren't overdoing it and creating a spammy page, and is also useful in making sure you haven't left something out completely. On page content is where density should come from. Google tries to think like a visitor to your web site. If they can't see the keywords, then G treats them as something that the visitor won't see. Metas can be used to tell G what you are trying to focus on with your site, but in my opinion, they should not factor into your own keyword density calculations. You should use your on-page content for your calculation. Your metas serve a more technical purpose. The stuff inside the body tags is what your visitor will see. Simply put, what you see as a human viewing a normal website is the data contained inside the body tags within the page source. It is a fairly common belief in the SEO world that Google puts much less value on metas while Yahoo and Bing give them more weight. G still looks at metas and can use them to help decide what your page is about, but it is more concerned with what the visitor is seeing, that information within the body tags. I agree with iamnameless: "Keyword density isn't that important anymore anyway". For many it has turned into more of a guideline on what seems to work most often, as a sort of general rule. You want to mention your keywords, but using things like related words and synonyms holds more value now in the eyes of many who work with SEO. The reasoning is simply that G seems to give everyone a relevancy value to their page as part of their overall calculations. I am sure that is not what G calls it, but basically G is smart enough to know that the guy repeating the same word every sentence on their page knows less about the subject than the guy with it appearing much less, but has synonyms and related keywords throughout the page. The real density that I believe site owners should be concerned with is keyword plus synonyms plus related terms vs all other on-page words.