In Google Analytics 4 (GA4), bounce rate is the percentage of sessions that are not engaged sessions. With the default timer, an engaged session lasts longer than 10 seconds, has a key event, or has at least two page or screen views. The time threshold can be adjusted in Google tag settings. Bounce rate equals non-engaged sessions divided by total sessions, multiplied by 100. It is also 100% minus engagement rate.
Example
If a website records 100 sessions and 65 are engaged sessions, its engagement rate is 65% and its bounce rate is 35%. A visit to one page can still be engaged, so a single-page visit is not automatically a bounce in GA4.
How to use this metric
Compare similar landing pages and acquisition channels, then review the page experience and measurement setup before deciding what to change. Interpret bounce rate alongside qualified inquiries or purchases. Email bounce rate measures undelivered messages and is a different metric.
Source: Google Analytics: engagement rate and bounce rate.
Related guidance
For the configurable time threshold, see Google tag settings.