Session key event rate in Google Analytics 4

Source: Analytics Help, Analytics dimensions and metrics.

Key events are the events you mark as key in GA4, such as a form sent, a purchase or a click on a phone link. GA4 used to call them conversions. The rate counts any of them unless you filter one in a report.

GA4 also has User key event rate: the share of active users with at least one key event. It is higher whenever people need two visits to act.

Versus the Google Ads conversion rate

The Google Ads conversion rate divides conversions by ad interactions. It differs from GA4's rate in four ways that matter.

• Google Ads counts only ad traffic. GA4's rate covers every session on the site.
• Google Ads can count several conversions per click, so its rate can pass 100%. GA4 counts a session once.
• Google Ads counts calls from call assets, which never reach the site. GA4 never sees them.
• Google Ads books a conversion on the day of the click by default. GA4 books the key event on the day it happens.

Worked example

A plumbing firm marks two key events: the quote form and a tap on the phone link. In May the site has 9,000 sessions, and 540 contain a key event: 6.0%.

Its Google Ads account shows 11% on 2,000 clicks the same month. Nothing is broken. A third of those Google Ads conversions are calls from call assets. And someone who clicks a plumber's ad usually has a leak to fix, unlike someone reading the blog.

1. In Google Analytics, open Reports, then Acquisition, then Traffic acquisition. Session key event rate is a default column.
2. Use the drop-down above the column to pick one key event instead of all of them.
3. To see which events count, open Admin, then Data display, then Events, and look at the Mark as key event switch.

Optizads has both versions in its Key events group: Session key event rate and User key event rate, with Key events, the raw count.

The rate is Google Analytics' own figure for the days asked, across all key events of the property. To follow one key event only, read it in GA4.

For ad traffic, Optizads stores Key events from ads and Visits from ads. A Calculated metric dividing the first by the second gives key events per ad visit. Read it as a count per visit, not as GA4's rate, since one visit can hold several key events.

• Putting it next to the Google Ads conversion rate as if one should equal the other.
• Marking page_view, scroll or a video start as key events. The rate rises and stops meaning anything.
• Importing a key event into Google Ads as primary while the Google Ads tag for the same action is primary too. One result is then counted twice.
• Reading a fall as fewer leads when a key event was unmarked that week.

• Key event: Google Analytics 4's name for an event you mark as important, such as a purchase or a sign-up.
• Conversion rate: Conversions divided by clicks.
• Conversion action: One definition of a conversion in Google Ads, with its source, its counting, its value and its window.
• Primary conversion action: A conversion action used for bidding and shown in the Conversions column.

• Sessions (GA4): A session in Google Analytics 4 is one visit to your site or app, opened by the session_start event.
• Sessions from Google Ads (GA4): Sessions from Google Ads are the GA4 sessions whose source and medium are google / cpc, which is how auto-tagged Google Ads clicks arrive.
• Engaged sessions (GA4): An engaged session in Google Analytics 4 is a visit that lasted longer than 10 seconds, viewed at least two pages or screens, or triggered a key event.
• All conversions: All conversions is the Google Ads column that counts every conversion the account records, including the actions not used for bidding.