The subject of keyword density has been open to debate for a long time. In the early days of search engine optimization, high keyword density was the order of the day, to the extent that you would have the same keyword repeated several thousand times on the page, in small print that matched the background color of the site.
Alternatively, you might have several hundred doorway pages that had a single phrase on them, for a 100% keyword density score. On today’s search engines, sites like these are almost guaranteed to be penalized for exceeding keyword density levels. Depending on who you ask, the best keyword density could be between 2% and 9% of your on-page content.
For people who write their own web content, keyword density can be problematic. Naturally, you don’t want to trip any filters in the search engines, but at the same time you shouldn’t have to pad your content with fluff and filler. One of our general rules is that you should be able to read your content out loud without sounding repetitive, but in some cases there are a few profitable keyword variations that would all do well on the same page, so the language can get a bit stilted. Generally, we try for a 4% density, but there are numerous outside factors that can move this figure up or down by a few percent.
First and foremost, your content should be useful to a real customer, even if it isn’t likely to be read. Second, you should make sure that your page’s best keywords are being represented in the body text, since your competitors who use SEO techniques are likely to do the same thing, and you want to be on a level playing field. Third, you should make sure you are optimizing enough pages to spread your keywords out efficiently. Normally you should be hitting a maximum of 3-4 keyword phrases per page.