Key events (conversions)

A key event is an event you have flagged as important: a purchase, a lead form, a sign-up. Until March 2024 GA4 called these conversions; the rename happened so that "conversion" means the same thing in Google Ads (an ad-driven key event). Older articles and the Google Ads UI still say conversions.

Marking one is a toggle, not code. In Admin > Events (or Admin > Key events) find the event name and switch Mark as key event. If the event has not been seen yet, create the key event by name in advance; it activates when the first one arrives. The flag is not retroactive: events before the toggle are not counted as key events.

You can have up to 30 key events per property (50 in 360). Each has a counting method: once per event (default, right for purchases) or once per session (right for leads, where one person submitting twice is still one lead).

Once flagged, the event appears in the Key events report, in acquisition reports as Key events and Session key event rate, in Explore as a metric, in the Advertising section's attribution and path reports, and, if linked, in Google Ads as an importable conversion. A session with a key event also counts as engaged.

A frequent mistake is marking page_view with a URL condition. GA4 cannot do that directly; instead, create a new event in Admin > Events > Create event that fires when page_view has page_location containing /thank-you, then mark that derived event as key. Better still, send an explicit generate_lead event from the form.