Bounce Rate

Bounce rate in GA4 is the share of sessions that were not engaged, the exact inverse of engagement rate.

GA4 redefined the word. It no longer means single-page visits, the way Universal Analytics used it. Now a session bounces only if it failed all three engagement conditions: under ten seconds, no key event, and fewer than two views. So a bounce is not "they left after one page," it is "they left without doing anything worth counting."

A visitor lands, spends twelve seconds reading a single page, and leaves. In Universal Analytics that was a bounce. In GA4 it is not, because twelve seconds clears the engagement threshold. Only the visitor who leaves in under ten seconds with one view and no key event bounces.

GA4 bounce rate and Universal Analytics bounce rate are not the same metric wearing the same name. The old number was usually far higher because any single-page visit counted. If you benchmark your GA4 bounce rate against an old target or an industry figure built on the Universal definition, you will read the result completely wrong. It is engagement rate subtracted from one hundred, nothing more.

Not "they left one page." "They left doing nothing."