[h=2]What is Keyword density in SEO?[/h] In common word, Keyword density is percentage of number of times Keyword appeared on a Web page by total number of words in that page. So if in an article of 100 words you are using your Keyword 10 times, your density will be 10%. Many people use different ways and formulas to calculate Key word density and here is one such formula.
(No. of Keywords/ Total number of Keywords) * 100
There are other Formulas too....
Idea of using Keyword many times in a Blog post is to make search engine bots understand your content better and you can rank for those Keywords. But, these was something which is thing of the past and now density of Keywords, value less and quality of site and site authority matters more. Though, it doesn't meant Keyword density doesn't hold any value in SEO, in fact it's one of the factor in On page SEO checklist.
[h=3]What's ideal Keyword density Percentage According to Google:[/h] One of the most common myth is if we use our keyword many time, we will rank higher in SERP's. There is no ideal or exact percentage for better ranking, though an optimum 1-3% of Keyword density along with Semantic Keywords and LSI Keywords works for me. If we talk about Google, Google suggest to write natural article with your Keyword in article. There is no ideal percentage but having your Keyword few times with natural occurring, will be helpful.