GA4 Key Events vs Conversions: Setup and Counting for Stores

GA4 reports have a Key events column where Conversions used to be. It looks like a simple rename, but key events and Google Ads conversions now have different jobs, and if you miss that distinction it’s hard to see why GA4 and Google Ads never report the same number.

This article covers what key events are, which events an online store should mark, how to set them up and choose a counting method, and how key events relate to Google Ads conversions, including why the numbers don’t match. Screens are as of October 2026. For the rest of GA4’s metrics, see GA4 Metrics Explained, and for the basics of reading GA4, see How to Use GA4.

What are key events in GA4?

Key events are the events sent to GA4 that you’ve decided to count as results, such as purchases or contact form submissions. Click the star next to an event name and it becomes a key event.

Key events vs conversions

GA4 used to call these conversions. Because Google Ads conversions had the same name but were counted differently, GA4’s side was renamed to key events. In the GA4 Data API, the change landed in May 2024, when the conversions metric was replaced by keyEvents.

Here’s how the names and roles split now.

Diagram of how events, key events and conversions relate. 1, in GA4, events record what happened on the site, such as page_view, add_to_cart and purchase. 2, in GA4, key events are the events marked with the star as results, formerly called conversions. 3, in Google Ads, conversions are key events brought into Google Ads to measure ad results and inform bidding. A note says the rename happened because GA4 and Google Ads both used the word conversion but counted them differently. — How events, key events and conversions relate. As of October 2026. Created by ULTRO Inc. based on Google Analytics Help. Click the image to enlarge.

As a table:

Name	Where it lives	What it does
Event	GA4	Records something that happened on your site (a page view, an add to cart, a purchase)
Key event	GA4	An event you’ve decided to count as a result
Conversion	Google Ads	A key event (or other action) brought into Google Ads to measure ads and inform bidding

A GA4 key event only becomes a conversion once it’s imported into Google Ads. Look at key events when you’re measuring results in GA4, and at conversions when you’re in Google Ads. For more on how events themselves work, see GA4 Events Explained.

Which events an online store should mark as key events

Event	What happened	Mark it?
purchase	A purchase	Yes. It’s a key event by default
begin_checkout	Checkout started	If needed: when purchases are too few for ad bidding to learn from
add_to_cart	Added to cart	If needed, but it makes the Key events total harder to read
generate_lead	Contact or quote request	Yes, if you take wholesale or B2B inquiries
sign_up	Account created	Yes, if growing sign-ups is a goal

purchase is marked as a key event by default. In the properties we’ve checked, its star is grayed out and it can’t be unmarked from the menu.

GA4 Admin > Data display > Events on the Key events tab. add_to_cart, begin_checkout, close_convert_lead, purchase, qualify_lead and view_item are listed with stars. The star next to purchase is pale, and its menu shows Change counting method, Set default key event value, Mark as NPA and a greyed-out Unmark as key event. Stream names are hidden — ① Key events tab ② The pale star for purchase ③ Change counting method (Unmark as key event is greyed out for purchase) (Screen as of October 2026. Click the image to enlarge.)

Some events get marked automatically by ads settings

If GA4 is linked to Google Ads with ads personalization turned on, events such as add_to_cart, begin_checkout, view_item and view_item_list can be marked as key events automatically. In a property we checked, add_to_cart, begin_checkout and view_item had all become key events this way.

Our own take: keep key events to a minimum. By default, the Key events column in reports is the total of all key events, so if view_item is a key event too, you can’t tell at a glance how many purchases there were. Open the key events list every so often and check that nothing is marked that you didn’t intend.

How to set up key events

In Admin, under Data display, click Events.
On the Recent events tab, click the star next to the event you want to mark.
Check that the event now appears on the Key events tab.

To mark an event that GA4 hasn’t received yet, click Create event, enter the event name and turn on Mark as key event. GA4 starts treating it as a key event once it’s collected. You can have up to 30 key events per property (50 on Analytics 360).

The two counting methods

You choose how each key event is counted. On the Key events tab, click the menu at the right end of the event’s row and choose Change counting method.

The Counting method (purchase) panel in GA4. Once per event is selected and marked Recommended, and Once per session is below it — ① Once per event (Recommended) ② Once per session (Screen as of October 2026. Click the image to enlarge.)

Counting method	How it counts	Best for
Once per event (recommended)	Every time it happens; two in one visit count as two	Purchases
Once per session	Once per visit, however many times it happens	Contact forms, quote requests, sign-ups

Once per event is the default for most key events. Key events created from Universal Analytics goals, whether automatically or through the goals migration tool, default to Once per session. If purchase is on Once per session, two purchases in one visit count as one, so check it.

Changing the counting method doesn’t touch past data; it only applies from that point on.

Importing key events into Google Ads

To use a GA4 key event as a Google Ads conversion, link GA4 and Google Ads first. Then in Google Ads, go to Goals > Summary, click Create conversion action, choose your GA4 property and select the events to import. You can also do it from GA4 under Advertising > Tools > Conversion management. For Enhanced Conversions, see Google Ads Enhanced Conversions. For the full Google Ads setup and how to check tracking when conversions aren’t recorded, see Google Ads Conversion Tracking.

Why GA4 and Google Ads numbers don’t match

Even after importing, GA4 key events and Google Ads conversions won’t match. The main reasons:

Difference	GA4	Google Ads
Date it’s reported on	The day the key event happened	The day of the ad interaction
Attribution credit	Can go to channels other than Google Ads	Only to Google Ads interactions
Attribution model	Set in the property	Set per conversion action
Lookback window	Set in the property	Set per conversion action
Time zone	Property setting	Ads account setting
Counting method	Key event setting	Conversion action setting

For example, if someone clicks an ad on the last day of the month and buys early the next month, Google Ads reports it in the month of the click and GA4 in the following month. For a fuller picture of why GA4, ad platforms and Shopify disagree, see Ecommerce Attribution.

If GA4 purchases are lower than your Shopify orders, there’s a separate cause besides counting differences: purchases where the tag never ran in the browser never reach GA4. If you import GA4 purchases into Google Ads, those orders are missing from your ad results too. How to check is in GA4 Not Tracking All Shopify Purchases?

We built a Shopify app, GapFill, that recovers missing GA4 purchase events server-side, sending only the orders GA4 never received. It’s our own product, so read with that in mind. It works alongside your existing tags, and the missing purchases report is free.

Our Shopify appGapFill: Recover missing GA4 purchase events server-sideWorks alongside your existing tags. Free missing purchases report.See GapFill →

Attribution settings

Change GA4’s attribution settings in Admin under Data display > Attribution settings. By default, the lookback window is 30 days for acquisition key events (first_visit, first_open) and 90 days for all other key events. Rule-based models such as first click and linear were retired in November 2023, so you now choose between data-driven and last-click models.

Reading key events in reports

Reports such as Traffic acquisition have Key events and Session key event rate columns on the right. Click All events under the column name and choose purchase to see the number of purchases and the share of sessions with a purchase.

Metric	Meaning
Key events	How many times key events were recorded
Session key event rate	Share of sessions with at least one key event
User key event rate	Share of users who triggered at least one key event

GA4 Traffic acquisition report with Session primary channel group (Default Channel Group) as the dimension. The Key events column has an All events dropdown, and the Session key event rate column also has an All events dropdown. Numbers are hidden — ① Key events with its All events dropdown ② Session key event rate (Screen as of October 2026. Click the image to enlarge.)

Because the default view totals all key events, filter to purchase before reading the numbers for an online store. How to read purchases by traffic source is covered in How to Use GA4.

Sources

FAQ

What's the difference between key events and conversions in GA4?

A key event is an event you've marked in GA4 as a result worth counting. A conversion is a key event (or other action) brought into Google Ads to measure ad performance and inform bidding. GA4 used to call key events conversions too; the name changed so the two wouldn't be confused.

Which events should an online store mark as key events?

Start with purchase, which is a key event by default. You can also mark begin_checkout or add_to_cart, but they get added into the Key events total in reports, so the more you mark, the harder the reports are to read.

How many key events can I have?

Up to 30 per standard property, and up to 50 per Analytics 360 property.

Which counting method should I use?

Keep purchase on Once per event so two purchases in one visit count as two. Use Once per session for events like contact form submissions or sign-ups that you want to count only once per visit no matter how many times they fire. Changes only apply going forward.

Why don't my GA4 key events match my Google Ads conversions?

They're counted differently. Google Ads reports a conversion on the date of the ad interaction, while GA4 reports it on the date the key event happened. Differences in which channels can receive credit, attribution models, lookback windows, time zones and counting methods also make the numbers drift.