The bounce rate is purely calculated from the number of entrances to the site for each page, rather than people visiting that page having already seen a page of your site within the same visit.

Bounce rate is an Internet marketing term used in web traffic analysis. It represents the percentage of visitors who enter the site and then leave rather than interacting with other pages within the same site.

Bounce rate is one of the most misunderstood metrics in Google Analytics. Bounce rate is the percentage of single page visits (or web sessions). It is the number of visits in which a person leaves your website from the landing page without browsing any further.