Conversion (Key Event)

A key event is simply an event you've told GA4 is important enough to count as a goal — a newsletter sign-up, a contact-form submission, a purchase. In 2024 Google renamed these from "conversions" to "key events" inside Analytics, keeping the word conversion for Google Ads. The mechanism didn't change; the label did. Any event can be marked as a key event with a single toggle.

Why it matters

Key events are how you turn raw activity into a measure of whether your site does its job. Pageviews and sessions tell you people showed up. Key events tell you they did the thing you actually wanted — booked a call, downloaded the guide, bought the product. Without at least one well-chosen key event, GA4 is showing you motion without telling you whether any of it pays off.

A concrete example

Say your goal is enquiry calls. You mark the generate_lead event — fired when someone submits your contact form — as a key event. Now GA4 reports how many sessions ended in an enquiry, which pages and channels produced them, and whether that count is rising or falling. Suddenly a vague "traffic is up" becomes "traffic is up and enquiries rose with it," which is a very different sentence.

The common misreading

The rename causes real confusion: people see "key events" in GA4 and "conversions" in Google Ads showing different totals and assume something is broken. They measure overlapping things from different perspectives, so they rarely match exactly. Don't reconcile them line by line — read each in its own context.