GA4 Key Events: Mark, Count and Verify the Actions That Matter

Google Analytics 4 (GA4) records everything as events: a page view, a scroll, a file download, a form submission. Most of those are background noise. A few matter to the business: a contact form sent, a purchase finished, a booking made. GA4 key events are how you tell the system which events those are, so reports can count them separately and show where they come from.

If you have read older tutorials, you will find the same idea called a conversion. This guide explains the current wording, then walks through choosing the action, getting an event to fire, marking it as a key event, choosing how it is counted and checking that it works. It is for site owners and small teams who already have GA4 collecting data. It does not cover advertising platforms in depth, and it cannot tell you what your goals should be.

Short answer: A key event is a GA4 event that you flag as important to your business, such as a form submit or purchase. Make sure the event is collected, then mark it in Admin under Data display, Events. Marking applies from that moment onward only, and standard reports can take up to 24 hours to show the change.

Before you begin

You need a GA4 property that receives data from your site, with the Editor role or above on the property to mark an existing event (creating a new event with the key event switch on needs Marketer or above, according to Google). If GA4 is not installed yet, start with GA4 setup for small business. If your tags run through Tag Manager, keep Google Tag Manager setup guide open, because most custom events are easiest to send from there.

Write down the three to five actions that show a visit was worthwhile. Google's help says a property can have up to 30 key events (50 for Analytics 360), and a long list makes reports harder to read.

Expect the work to take under an hour once the event fires. Nothing here changes your pages, so the risk is low. If a thank-you page should stay out of search results, see What Does Noindex Do?; noindex does not stop analytics tags firing, but test to be sure. One caution: marking an event is not retroactive. It affects reports from the time you mark it and does not change historic data.

Are key events the same as conversions?

Almost. Google announced in March 2024 that conversions in Analytics reports would become key events, so that a conversion means the same thing in Google Ads and Analytics. Today Google Analytics Help describes the path as Event, then Key event, then Conversion:

A key event is an event that measures an action important to your business, used for behaviour and traffic analysis in the Reports and Explore areas of Analytics.
A conversion is a key event that you share with Google Ads, to measure ad performance and optimise bidding. Google's help notes you can create a Google Ads conversion from a key event, and that Google Ads conversions do not appear in standard Analytics reports.

If you do not run Google Ads, you only deal with key events. If you do, mark the key event in Analytics first and create the Ads conversion from it afterwards. Google's key events page says reports such as Landing pages and User acquisition include a Key events column.

What kinds of events can become GA4 key events?

Any event GA4 collects can be marked. Google groups events into four kinds:

Kind	How it gets into GA4	Examples
Automatically collected	Collected by default once GA4 is set up	`page_view`, `session_start`
Enhanced measurement	Collected when enhanced measurement is on for the data stream	`scroll`, `file_download`, `form_start`, `form_submit`
Recommended	You implement them, using Google's predefined names and parameters	`purchase`, `generate_lead`, `sign_up`, `login`
Custom	You define the name yourself	`quote_requested`, `brochure_requested`

Google advises creating a custom event only when no other event suits the use case. Prefer a recommended event name when one fits, because those names carry predefined parameters that reports understand.

Check the form events before you trust them. Enhanced measurement lists form_start ("the first time a user interacts with a form in a session") and form_submit. How well they detect your form depends on how it is built, so test it.

Step-by-step instructions

Step 1: Choose the action and the page or signal that proves it

Pick one action, then decide what proves it happened: a thank-you page that only appears after success, a confirmation event sent by your site's code, or the purchase confirmation. A click on a Submit button is weaker, because it fires even if the form fails validation.

For an online shop, use the recommended purchase event. Google lists transaction_id and items as required for purchase, and value plus currency as needed for meaningful revenue reporting. For lead forms, generate_lead is the recommended name. Google says value is typically required for meaningful reporting, and that if you set value you also need currency.

What success looks like: A written line such as "Contact form sent: fires on the confirmation page at /contact/thanks".

Step 2: Make the event fire

You have three common routes.

Enhanced measurement. In Admin, open Data streams, choose your stream and check that Enhanced measurement is on and the form interactions option is enabled. This needs the Editor role. Use it only if your form triggers it, and confirm by testing.
Create an event from an existing one. In Admin, under Data display, click Events, then Create event. Name the new event, then add matching conditions. For a thank-you page, match event_name equals page_view and page_location contains /contact/thanks. Google advises the "equals" operator over "equals (ignore case)" if you want an exact match. These rules apply going forward only, and an hour or more can pass before modifications take effect. Google's page also says you can create up to 50 events this way.
Send the event from your site or Tag Manager. This is best for complex forms and shops. Your developer or tag setup sends generate_lead or purchase with its parameters when the real success moment happens.

Event names are limited to 40 characters. Google's collection limits page says that if you mark an event as a key event and its name exceeds 40 characters, it will not be reported as a key event. Google says special characters are not allowed in the name of a new event, so keep it plain.

What success looks like: The event name appears in your event list after you complete the action yourself.

Step 3: Confirm the event arrives with DebugView

Before you mark anything, test it. Google's DebugView shows events from devices that have debug mode on. You can turn it on for your own browser with Tag Assistant or Tag Manager preview mode, or set debug_mode to true on the config command or on selected event commands in gtag.js. Setting it to false does not turn it off; leave the parameter out.

Open Admin, then DebugView under Data display. The Seconds stream lists events from the last 60 seconds; click one to see its parameters. If nothing appears, Google notes that events will not show when client-side privacy controls are in place, or when consent mode is active and the visitor has not agreed to analytics cookies. See Google Consent Mode for GA4 for that case.

What success looks like: DebugView shows the event once per completed action, with the parameters you expect.

Step 4: Mark the event as a key event

For an event that already exists in the list: in Admin, under Data display, click Events, find the event in the Recent events tab and click the star icon next to it. That marks it as a key event.

For a new event: choose Create event, enter a name, switch on "Mark as key event", pick a default key event value and a counting method, then click Create. Google notes you can mark an event ahead of time, and Analytics will treat it as a key event once it is collected.

After marking, open Admin and Key events under Data display to see the list. Standard reports can take up to 24 hours to show the change, while realtime reports update within a few minutes.

What success looks like: The event is listed under Key events and a Key events column appears in reports.

Step 5: Choose the counting method

Each key event has a counting method, and you can change it from the Key events list (use the menu at the end of the row and pick Change counting method; you need Marketer or above).

Method	What it counts	Typical use
Once per event (Recommended by Google)	Every time the event fires	Purchases, where each order counts
Once per session (Legacy)	At most once in a session per user	A lead form where repeated submits should count as one

Google's example: five triggers in one session count as five under Once per event and one under Once per session. Events created from migrated Universal Analytics goals default to Once per session, and all others default to Once per event. A change affects future events only, not past data. Pick the method that matches how you will use the number.

What success looks like: The count of a test action in a session matches your choice.

Step 6: Verify in reports and set a baseline

Let a day pass, then check a report with a Key events column, such as Landing pages or User acquisition. Compare the number with a source you trust: the form tool's own submissions or the shop's order list. Small gaps are normal because of blockers, privacy settings, consent choices and timing. Large gaps usually mean the event fires at the wrong moment or twice. Extra tags also add weight to the page; see Third-Party Scripts and Performance.

To see which search queries and pages bring visits, use the Search Console Performance report. If you use the Search Console link, GA4 Search Console Integration shows how to compare search visits with key event counts without mixing up the two data sources. To see which campaigns drive your key events, tag your links as described in the UTM parameters guide.

What success looks like: GA4's count and your own records agree closely enough that you would make a decision from it.

What can go wrong with key events?

Work through these checks in order when numbers look wrong.

No event at all. If DebugView does not show it, the problem is the tag or trigger, not the key event setting.
Event exists but is not a key event. Check the Key events list, and the 40-character name limit.
Counts too high. The thank-you page is reloaded, or the trigger fires on every field. Use a more specific trigger, or switch to Once per session.
Counts too low. Consent choices, blockers and failed scripts reduce what is collected. Compare trends rather than demanding a perfect match.
Personal data in parameters. Google's enhanced measurement guidance says you must make sure no personally identifiable information is collected.

Final verification checklist

The action and its proof (page, signal or order) are written down.
The event name is within 40 characters and uses a recommended name where one fits.
DebugView showed the event once per completed test action.
The event is listed under Key events in Admin.
The counting method matches how you will use the number.
A report with a Key events column shows the event after processing time.
The count was compared with the form tool or order list.
You have fewer than 30 key events on a standard property.
The date each event was marked is recorded.

Common mistakes to avoid

Marking a button click as the success signal. A click happens before the form passes validation. Fix: fire on the confirmation page or event.
Marking too many events. Reports become noisy. Fix: keep only actions you will act on.
Expecting history. Marking does not rewrite old data. Fix: note the mark date.
Long event names. Names over 40 characters are not reported as key events. Fix: shorten them.
Skipping DebugView. Fix: test before marking, and again after site changes.
Forgetting the counting method. Fix: decide per event and write it down.
Treating key events and Ads conversions as one report. Google Ads conversions do not appear in standard Analytics reports. Fix: compare each in its own interface.

Frequently asked questions

What is the difference between a key event and an event in GA4?

Every action GA4 collects is an event. A key event is an event you have flagged as important to the business. Any collected event can be marked, but not every event should be.

How many key events can I have in GA4?

Google's help states up to 30 key events for standard properties and 50 for Analytics 360 properties.

How do I mark a form submission as a key event?

Make sure a form submit event arrives, either through enhanced measurement, a created event matching your thank-you page, or one your site sends. Then star it in Admin, Data display, Events, or create it with Mark as key event switched on.

Why do I not see my key event in reports?

Standard reports can take up to 24 hours to show a change. Also confirm the event reached DebugView and that its name is within 40 characters.

Are key events retroactive?

No. Google says marking an event as a key event affects reports from the time of creation and does not change historic data.

Official references

Next step: Try the free website sample to see how your own site does on a few of these checks. This guide provides technical information, not a guarantee of rankings, traffic or index inclusion.