Keyword density is the percentage of keywords contained within the total number of indexable words within a web page, or to put it another way, the ratio of a keyword or key phrases to the total number of words on that page. If the keyword density is too high, you run the risk of keyword stuffing. If the density is too low, you run the risk of not ranking well. There is no right or wrong keyword density, as the proper level can be different for every phrase. Some pages rank well with rather high density, some with very low density. If you've used your keywords a few times within the page, and the page makes sense when read by a human, you've probably hit upon a fairly decent density. Like everything, keyword density is only one of many ranking factors, so don't spend all your time stressing about it. You can use the free keyword density analyzer below to compare the density between your page and your competitor's page.