Keyword density is the percentage of the number of times a keyword appears on a page divided by the 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%. There is no ideal or exact percentage for better ranking. There is no ideal or exact percentage for better ranking. But idealy, 1-3% of keyword density along with “semantic keywords” and LSI keywords works best.