What is Engagement rate?
Engagement rate is the percentage of visits that qualified as engaged — typically by lasting beyond a set number of seconds, seeing more than one page, or triggering a conversion. GA4 popularised it as a replacement for bounce rate. Since the qualifying threshold is set by the tool, the same site can post very different engagement rates in different products.
The definition to check first
GA4 counts a session as engaged if it lasts longer than ten seconds, includes a conversion event, or has at least two pageviews. Ten seconds is a configurable threshold, and other tools pick different rules entirely.
So the first question about any engagement rate is not “is it good” but “what qualified”. A rate of 62% under a ten-second rule and 62% under a thirty-second rule describe materially different audiences.
Why it replaced bounce rate
Bounce rate counts an absence: nothing else happened. That made sense when a visit meant loading several documents, and stopped making sense once a single page could hold an entire application, a video, and a form.
Engagement rate counts a presence instead, which is both harder to misread and more robust to how a site is built. The two are complements — engagement rate is approximately 100% − bounce rate when the thresholds happen to align, which is not often.
The ceiling problem
Because engagement is a threshold, the metric saturates. Once most visits clear ten seconds, the rate sits near 90% and stops moving, and a genuinely better page produces the same number as a merely adequate one.
When that happens, stop optimising the rate and move to something with headroom: engaged time as a distribution, scroll depth, or the conversion rate the engagement was supposed to predict. A metric that cannot get worse is also a metric that cannot tell you anything got better.