If you've been using GA4 (Google Analytics 4), you've likely noticed the term "key event" appearing more frequently. In March 2024, Google renamed what was previously called "conversions" to "key events," significantly changing the terminology used in the admin panel and reports.
This article provides a comprehensive guide covering the basic concept of GA4 key events, how they differ from conversions, specific setup methods, and how to troubleshoot common issues.
A key event is an event that measures actions particularly important to your business outcomes, selected from among all the events tracked in GA4. GA4 tracks all user actions on your website or app (page views, clicks, scrolls, etc.) as "events," but by marking those that directly contribute to business results as key events, you can accurately evaluate the effectiveness of site improvements and marketing initiatives.
For example, on an e-commerce site, "purchase completion" would be a key event. For a B2B site, it might be "contact form submission," and for a media site, "article read to completion." You can set up to 30 key events, and users with administrator or editor-level permissions can modify them.
On March 27, 2024, Google officially announced the change from "conversions" to "key events" in GA4. The motivation behind this change was to resolve confusion between GA4 and Google Ads.
Previously, both GA4 and Google Ads had metrics called "conversions." However, since the two platforms used different measurement methods, even when the same user actions were set as conversions, the numbers wouldn't match. This frequently caused confusion in advertising operations about which conversion numbers to trust.
To resolve this confusion, Google renamed the GA4 metric to "key event" and unified "conversion" as a term exclusively for Google Ads performance measurement. This makes cross-platform reporting and analysis much simpler.
After the name change, GA4 now clearly distinguishes between three concepts: events, key events, and conversions.
An "event" refers to any user action that occurs on your website or app, such as page views (page_view), scrolls, and file downloads.
A "key event" is an event that has been marked as particularly important for your business. It can be used as a performance metric in GA4 reports and explorations, and is measured across all traffic channels (search, social, email, ads, etc.).
A "conversion" is a metric created on the Google Ads side based on key events. It's used for ad campaign bid optimization and performance measurement, with consistent numbers shared between GA4 and Google Ads. The key point is the hierarchical structure: Event → Key Event → Conversion.
There are two main methods for setting up key events. Let's start with the simpler method that can be completed entirely within the GA4 admin panel.
Setting up events that GA4 is already tracking (page_view, scroll, file_download, etc.) as key events is very straightforward. Open "Admin" from the bottom of the sidebar in the GA4 admin panel, select "Events" from the "Data display" section. When the event list appears, simply toggle on "Mark as key event" next to the event you want to designate.
If you want to make an action that isn't tracked by default into a key event, such as "reaching the contact completion page," you'll first need to create a custom event.
Click "Create event" on the Events page in the admin panel, then select "Create" for custom events. Enter an event name (e.g., contact_thanks) and set matching conditions such as "Parameter: event_name, Operator: equals, Value: page_view" and "Parameter: page_location, Operator: contains, Value: /contact/thanks." Once saved, the new event will be tracked whenever matching actions occur.
Once the event starts being tracked, toggle on "Mark as key event" next to the new event name in the event list to complete the setup.
For tracking events with complex conditions or efficiently managing multiple events, setting up via GTM (Google Tag Manager) is recommended. GTM allows flexible event configuration without directly editing your site's source code.
The GTM setup process is as follows. First, log in to GTM and create a new trigger from the "Triggers" menu. Choose the trigger type (pageview, click, etc.) and specify the firing conditions. For example, to track a thank-you page visit, use the "Page View" type with the condition "Page URL contains /contact/thanks."
Next, create a new tag from the "Tags" menu and select "Google Analytics: GA4 Event" as the tag type. Enter your GA4 Measurement ID (the ID starting with G-), set a custom event name (e.g., contact_complete), and link the trigger you created earlier. Save both the tag and trigger, then click GTM's "Publish" button to start sending event data to GA4.
After publishing, check the event list in the GA4 admin panel. When the event sent from GTM appears, toggle on "Mark as key event."
GA4 key events offer two counting methods. The default is "Once per event," which counts every time a key event occurs. For example, if a user submits a contact form twice within the same session, the key event count is 2.
The other option is "Once per session." Even if a key event occurs multiple times within the same session, it's counted only once. Google's official documentation recommends the "Once per event" setting, as it allows you to distinguish between sessions with multiple key events and sessions with just one.
If you've set up a key event but data isn't appearing, check the following points.
First, it can take up to 24 hours for data to be reflected after setup. If you want to verify immediately, use GA4's Realtime reports or DebugView.
If using GTM, verify in Preview mode that tags are firing correctly. When tags aren't firing, the most common causes are trigger condition errors (URL typos, missing variable settings, etc.).
Also verify that your GA4 Measurement ID (starting with G-) is correctly set in GTM or on your website, and that event names comply with naming rules (alphanumeric characters and underscores only, no spaces). Additionally, if specific IP addresses are excluded in GA4's data filters, key events won't be tracked from those IPs.
Keep these important points in mind to use key events effectively.
First, be selective with the number of key events you set. While you can set up to 30, marking every click or scroll as a key event will inflate your numbers and render the analysis meaningless. Only designate actions that directly contribute to business outcomes.
Second, the purchase event is registered as a key event by default and cannot be removed. For apps, first_open and in_app_purchase are similarly fixed.
Third, data collection begins from the moment you mark an event as a key event, meaning you cannot retroactively aggregate past data as key events. It's important to set up necessary key events early, especially when launching a new site or first implementing GA4.
Fourth, setting up events in both the GA4 admin panel and GTM risks duplicate tracking of the same event. Establishing team rules like "create all new events in GTM" helps prevent this.
Key event data can be viewed in both GA4's standard reports and exploration reports.
In standard reports, you can check key event occurrence counts via Reports → Engagement → Events. To view key event counts by page, the "Pages and screens" tab is useful.
For more detailed analysis, use exploration reports. Select "Explore" and choose "Free form," then add "Event name" or "Page path" as dimensions and "Key event count" as a metric. This enables flexible analysis of key event occurrences by traffic source or page.
If you're running Google Ads, you can create Google Ads conversions based on the key events set in GA4. This allows you to directly leverage key event data for ad campaign bid optimization and performance reporting.
The process involves linking your GA4 and Google Ads accounts, then registering events marked as key events in GA4 as conversions on the Google Ads side. This integration enables consistent performance measurement across both platforms, improving the accuracy of your advertising investment decisions.
GA4 key events are the renamed version of the former "conversions" and serve as a core feature for measuring and analyzing user actions important to your business. By separating the naming from Google Ads conversions, the meaning of metrics on each platform has become much clearer.
Setup is as simple as toggling on a switch in the GA4 admin panel, but using GTM enables flexible event configuration for complex conditions. Set up the right key events for your site's objectives and leverage them for data-driven site improvement and marketing optimization.
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