Key events are the events you mark as the outcomes that matter, such as a trial sign-up, demo request or purchase. Google Analytics 4 called these conversions until 2024, when it renamed them key events. The word conversion in GA4 now refers to key events that are also used for Google Ads bidding and measurement, which keeps the two concepts separate.
Why the rename happened
Teams often saw different conversion numbers in GA4 and Google Ads and assumed one was wrong. The two systems count differently: different attribution models, different windows, and Ads only credits its own clicks. Calling the analytics version key events and reserving conversions for what Ads uses makes the distinction explicit.
Choosing key events
Mark only events that represent real progress toward revenue. For a SaaS site, that usually means a handful of events rather than dozens.
- Trial or free plan sign-up
- Demo or sales contact request
- Purchase or plan upgrade
- Possibly a high-intent micro step, such as pricing calculator use, if you report it separately
How key events affect other metrics
Any session with a key event is an engaged session, so adding a key event that fires often will raise engagement rate. Key events also drive GA4's attribution reports and the key event rate metrics. Treat changes to the list as a measurement change and annotate them.
Example
Cleaning up a crowded list
Imagine Mossbridge, a scheduling SaaS, has fourteen key events, including scroll and video_start. Every report shows high conversion numbers that no one trusts. The team reduces the list to sign_up, demo_request and purchase, keeps the others as plain events, and annotates the change date so year-over-year reports are read correctly.
Common mistakes
Marking engagement events as key events
Scrolls and clicks inflate engagement and dilute attribution. Keep key events for business outcomes.
Expecting GA4 and Google Ads to match
They use different attribution and counting rules. Reconcile the definitions instead of expecting identical numbers.
Questions
No. Marking an event as a key event applies from that point forward. Past occurrences are not reclassified in standard reports.
