When calculating the density of a keyword phrase, the formula would be ( N k r ∗ N w p / T k n ) ∗ 100 {\displaystyle (Nkr*Nwp/Tkn)*100} ,[1] where Nwp is the number of words in the phrase. So, for example, for a four-hundred word page about search engine optimization where "search engine optimization" is used four times, the keyword phrase density is (4*3/400)*100 or 3 percent.