How is bounce rate defined in GA4?

Now that we’ve established how Universal Analytics defined bounce rate let’s turn that idea completely on its head. On July 1, 2023, Universal Analytics stopped processing data for non-360 customers. UA has been replaced by GA4. In GA4, bounce rate has an entirely different definition. As a result, bounce rates for your website can be quite different in GA4, compared to what they were in UA.

To fully understand the Google Analytics 4 definition of bounce rate, it is important to review the concept of an engaged session, which has been introduced for GA4. Google defines an engaged session as:

• A session that lasts longer than 10 seconds,

• has a conversion event,

• or has at least 2 pageviews or screenviews.

If any of these criteria are met, a session will be considered ‘engaged’. Bounce rate in GA4 is the percentage of sessions that were not engaged.

Using this concept of an ‘engaged’ session, Google has created a new metric called engagement rate. Engagement rate aims to measure the percentage of users you visit your site

Engagement rate is defined as:

GA4 Engagement Rate = (Engaged Sessions / Total Number of Sessions) ×100

Bounce rate in GA4 is simply the inverse of engagement rate:

GA4 Bounce Rate = (NON-Engaged Sessions / Total Number of Sessions) ×100

In GA4, engagement rate, and bounce rate are exact opposites of each other. When you’re optimizing your website, you want your engagement rate to go up, and your bounce rate to go down. The metrics will always move in equal magnitude and opposite directions.

Why did Google change the definition of bounce rate in GA4?

GA4 more accurately measures modern web behavior than its predecessor, Universal Analytics. Web design has changed in many ways since bounce rate was first introduced around 2007, and so has the idea of what constitutes a ‘good’ or ‘successful’ website visit. By creating an engagement rate, and repurposing bounce rate as its direct counterpart, Google is better able to classify ‘successful’ or ‘engaged’ sessions on the modern internet.

Here’s an example: If you have a landing page with a video, some content, and a phone number call-to-action at the bottom, a visitor can become a customer all without visiting another page on your site. They could watch the video, read all of the content, and click the phone number to call you, all while being considered a ‘bounce’ by Universal Analytics. If every person to view this page completed this same journey, your bounce rate would still be 100% in Universal Analytics. Not a great measurement of how your audience engages with your content.

When GA4 was first launched, Google actually decided to remove bounce rate from its reporting capabilities entirely. To me, this illustrates that bounce rate still does have value from a KPI tracking standpoint, even if it is no longer a unique metric. Google likely took reporting continuity into account as well, in its decision to reintroduce bounce rate into GA4.

It is now the inverse of a new metric, engagement rate, but can still serve as an interesting data point in your user engagement reports and dashboards. However, keep in mind that the definition of bounce rate is completely different than it was in UA, and your data will look different. Users can continue reporting on a metric called ‘bounce rate’, in GA4, though the definition is completely different compared to UA.