Deep link ratio is a search engine optimization (SEO) metric that measures the proportion of pages on a website that are linked to from other internal pages. It is calculated by dividing the number of unique internal links by the total number of pages on the site.

The deep link ratio is used to assess a website's internal linking structure and its effectiveness in distributing link equity (or “link juice”) throughout the site.

A higher deep link ratio suggests that a website has a well-structured internal linking architecture, which can help search engines discover, crawl, and index pages more efficiently. This, in turn, can improve the site's overall SEO performance and search engine rankings.

A good deep link ratio is considered to be around 0.5 or higher, meaning that at least half of the website's pages have internal links pointing to them. However, the ideal ratio may vary depending on the size and complexity of the site, as well as its specific structure and goals.

Some SEO professionals use the deep link ratio as part of a comprehensive website audit to identify areas for improvement in internal linking, content organization, and site navigation.

By optimizing the deep link ratio, websites can enhance user experience, improve search engine visibility, and potentially drive more organic traffic to their pages.