Keyword density is a percentage of keyword by the total word content on a given web page.
Suppose you have 100 words on your webpage, and you use a keyword for five times in the content. The keyword density on that page is 5 divided by 100 = 5%. The accepted standard for a keyword density is between 3% and 5%, to get recognized by the search engines and you should never exceed it. Higher Keyword density can be considered spam by search engine.
To check the density, copy and paste the content into a word-processing software program like Miscrosoft Word. Go to the ‘Edit’ menu and click ‘Select All’. Now go to the ‘Tools’ menu and select ‘Word Count’. This is the number of words in the page. Now select the ‘Find’ function on the ‘Edit’ menu. Go to the ‘Replace’ tab and type in the keyword you want to find. ‘Replace’ that word with the some word, and when it is completed, the system will provide a count of the words you replaced. That gives the number of times you have used the keyword in that page. Get the keyword density by dividing total word count with total number of keywords.