Session key event rate = sessions with a key event ÷ all sessions
64 ÷ 1,600 = 4 percent
Why did Google rename conversions in GA4?
To stop two products using one word for two different counts. Before the change, a "conversion" in GA4 and a "conversion" in Google Ads could show different numbers for the same action, because they counted by different rules. Google renamed the GA4 version key events, and kept conversion for the actions used to measure and bid in Google Ads (Google Analytics Help, About key events). Existing GA4 conversions became key events automatically, and the counting did not change. Some report columns did, such as conversion rate, which became key event rate.
Which events should become key events?
The ones that bring money or reliably lead to it. GA4 records plenty of events by itself: page views, scrolls, first visits, clicks on links to other sites. Any of them can be marked as a key event in the Admin section, and that is the trap. Mark scrolls as a key event and every reader who reaches the bottom of a page counts as a success.
A useful test: would you be pleased if this action happened 100 more times next month? A form sent, yes. A scroll, no.
What should a Tamworth music school mark? (example figures)
A music school in Tamworth teaches guitar and piano and takes trial lesson bookings through its website. Its web developer set up two custom events, the trial form and a tap on the phone number, alongside the events GA4 collects automatically. One month:
| Event | Count | Key event? |
|---|---|---|
| Page views | 4,900 | No, every visit has them |
| Scrolls to the bottom of a page | 1,150 | No, reading is not booking |
| Clicks on a link to another site | 210 | No, mostly the teachers' YouTube channels |
| Trial lesson form sent | 41 | Yes |
| Tap on the phone number | 27 | Yes |
With those two marked, 64 of the month's 1,600 sessions included a key event (a few people did both), a session key event rate of 4 percent. Before the clean-up the school had also marked scrolls, and its report showed a rate several times higher that meant nothing. Now the key events report, split by channel, shows that Google search sends most of the trial bookings and Instagram sends most of the scrolling.
How do key events reach CoraVision?
CoraVision reads key events from Google Analytics 4 every night once it is connected, along with visits by channel, purchases and revenue, so the events you mark decide what CoraVision counts from GA4. That makes the marking step worth getting right. If a scroll or a page view has been marked by mistake, Cora can show you where the key events list sits in GA4's Admin during a session, and you unmark it yourself.
Questions
Do I still need conversions in Google Ads if I have key events?
If you run Google Ads, yes. Bidding works from Google Ads conversions, not from GA4 key events. With the two accounts linked, you can create a Google Ads conversion from a GA4 key event, so the action is defined once and used in both places.
How many key events should a small business have?
As few as tell the story. For most owner-led businesses that is the action that brings money (a purchase, a booking, an enquiry) plus perhaps a phone tap. Every extra key event dilutes the figure, and a report where everything is a key event says nothing.
Why do my GA4 key events not match my Google Ads conversions?
They count by different rules. GA4 credits key events across every channel it sees, while Google Ads credits only its own ads, reports a conversion against the day of the click, and handles visitors who declined cookies in its own way.