The essentials
- Definition: a key event is a GA4 event you mark as important for your business (a form submitted, a call, a purchase); it is the old "conversion" name, renamed in March 2024 to separate GA4 measurement from Google Ads conversions.
- How many: 5 to 10 key events in a hierarchy (primary and secondary), not 30.
- The method: the event has to exist (collected automatically, recommended, or custom through GTM), then it is marked in one click in Admin.
- How to use it: acquisition reports by key event, import into Google Ads as a conversion, audiences.
In GA4, everything is an event: a page viewed, a click, a form submitted. Among them, those that matter to the business are marked as key events . They were called "conversions" until March 2024; Google renamed them to reserve the word conversion for Google Ads, which imports GA4 key events under that name. This article explains what to mark, how, and how to read the results.
What changed with the renaming
| Before March 2024 | Since | |
|---|---|---|
| Name in GA4 | Conversion | Key event |
| Name in Google Ads | Conversion | Conversion (unchanged), from importing a GA4 key event |
| Counting | Once per event or per session | Unchanged, adjustable per event |
| Limit | 30 per property | 30 per property (50 in GA4 360) |
| Reports | The Conversions report | The Key events report, with "key events" and "session key event rate" columns |
Nothing changes in the data; only the labels and the naming logic. The old conversions became key events automatically.
Which key events to mark
A key event corresponds to an action that has value for the business. Put them in a hierarchy: two or three primary ones (a sale, a quote request), and secondary ones signalling interest (a download, a sign-up, a call).
| Business | Primary key events | Secondary |
|---|---|---|
| Brochure site, B2B services | A contact or quote form submitted (generate_lead), a call clicked | A brochure download, a webinar sign-up, the pricing page viewed for more than 30 s |
| E-commerce | A purchase (purchase) | Add to basket, checkout started, account created |
| Local business | A call, directions, a booking | A click through to the Google listing, a form |
| SaaS | A trial sign-up (sign_up), a subscription | A demo requested, the pricing page, documentation consulted |
| Media, content | A newsletter sign-up, a subscription | 75% read, a share |
Avoid marking traffic events (page views, scrolls): they inflate the key event count and make the reports unreadable. The event types are covered in GA4 events: definition and types.
Setting up a key event in four steps
- Make the event exist. Three cases: it is collected automatically or by enhanced measurement (an outbound
file_download,form_submit,click); it is sent by your site or GTM with a recommended name (generate_lead,purchase,sign_up); or you create it in GA4 (Admin, Events, Create event) from an existing event with a condition, for examplepage_viewwith apage_locationcontaining "thank-you". Setup through GTM is described in GA4 with Google Tag Manager. - Check it comes through in Admin, Events (a few hours' delay) or in real time with DebugView.
- Mark it : Admin, Key events, "New key event", enter the exact name. Or switch on the toggle in the events list. The name must be exact and is case-sensitive.
- Set the counting and the value: "once per event" (purchases, forms) or "once per session" (a visit to a key page); a default value if the event carries none (for example €50 per quote request, calculated from your conversion rate and average order value).
The complete procedure, with the use cases, is in turning on conversion tracking in GA4.
Putting key events to use
- Acquisition reports: in Traffic acquisition, choose a key event in the selector to see how many each channel generates and at what rate per session. That is the basic reading for deciding between channels; see how to read a GA4 report.
- Paths and attribution: Advertising, Conversion paths, to see the channels contributing before the last click; see attribution in GA4.
- Google Ads: import the key events as conversions (Goals, Conversions, New action, Import, GA4) to steer automated bidding on real enquiries. Choose a single primary event per objective so nothing is counted twice.
- Audiences: users who triggered a key event (or didn't) feed your remarketing and exclusion audiences.
- Dashboard: key events by channel, by entry page and by campaign, with the cost per key event for paid channels, in a single monthly report.
The frequent mistakes
| Mistake | Consequence | Fix |
|---|---|---|
Marking form_submit from enhanced measurement with no condition | Counts internal searches and newsletters as enquiries | Create an event conditioned on the form or the thank-you page |
| Counting a reloaded thank-you page once per event | Duplicates | Counting per session |
| Marking 20 events with no hierarchy | Unreadable reports, Google Ads optimising on noise | 2 to 3 primary, 5 secondary at most |
| A different event name on the site and in GA4 (a capital, an accent) | The key event counts nothing | The exact name, in lower case, with underscores |
| Not setting a value | No way to calculate a return on investment | A fixed value per event, or a dynamic value for e-commerce |
How GreenRed helps
Rather than juggling several tools, GreenRed's GA4 Performance and traffic module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
What is the difference between a key event and a conversion in GA4?
None in the data: "key event" is the new name for GA4 conversions since March 2024. Google reserved the word conversion for Google Ads, which imports GA4 key events as conversions to optimise campaigns.
How many key events can you create in GA4?
Up to 30 per property in the standard version (50 in GA4 360). In practice, 5 to 10 is enough; beyond that, the reports become unreadable and Google Ads' automated bidding optimises on actions with no value.
Should enhanced measurement events be marked as key events?
Rarely as they stand. Enhanced measurement sends generic events (form_submit, file_download, click) covering every form and every file. Create a conditioned event instead (a specific form, a thank-you page, a specific file) and mark that one.
Are key events retroactive?
No. An event marked as key is only counted from the moment it is marked. Earlier data for the event stays visible in the events reports, but not in the key event columns and reports. Mark them as soon as GA4 is set up.