GA4 Conversion counting method – does it matter?
About a week ago Google released a conversion counting method setting in GA4, which allows you to configure how you want to count each conversion. Currently, you can pick from 2 options – “Once per event” and “Once per session”.
I did a few tests of this setting, and in this article, I will share how the GA4 conversion counting method affects your data and my subjective opinion on that.
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Where can I find and change the GA4 conversion counting method setting?
Navigate to the Admin section of GA4 and from property column pick “Conversions”. You will see a list of all events marked as a conversion.
If your conversion is set to count “Once per session” you will see an additional icon displayed next to it. Conversions without an icon are using the “Once per event” counting method.
To edit the conversion counting method click on “3 vertical dots” menu and select “Change counting method”.
Then you can pick one of two counting methods:
- Once per event – Will count every event occurrence as a conversion
- Once per session – Will count conversion only once per session
Once you change and save it, GA4 will use a different methodology to count any new conversion events.
NB! This change is not retroactive (doesn’t affect historical data). If you’ll look at any time period before the counting method was changed – you’ll see a conversion count that is based on the previous counting method.
- Default conversion counting method will almost always be “Once per event” (when creating new event or marking existing events as conversions in GA4 UI).
- Conversion will have “Once per session” counting method only when you automatically migrate Universal Analytics goals or Properties to GA4 (to closely match conversion count you see in UA).
How it affects data in GA4?
To test how the conversion counting method affects data inside GA4 I’ve created 2 identical conversion events and set a different counting method for each.
- pv_conversion_every (Once per event)
- pv_conversion_session (Once per session)
They had a simple setup and both events were triggered when visitors viewed the same page.
First of all, you will see differences in real-time and debug view. While both events appear as conversions when first page view is made, only event-scoped conversion will be marked as a goal on second page view.
In the real-time reports you will notice some differences as well. The event count for both conversion events remains the same (because the event is collected on each interaction regardless of the selected counting method), but the conversion count, as expected, will be lower for events with “Once per session” setting.
As expected, aggregated default reports will tell the same story – we will see fewer conversions for “Once per session” option with the same total event count.
You won’t see any differences when looking at the conversion rate in GA4. It will still be the same for any chosen conversion counting option and affects only the “Conversion” metric itself.
Here is an example of looking at conversion rates for both of these events:
We have the same conversion rate metrics which means in the background it’s still the same event-based tracking and we can get pretty much the same results for any conversion type.
Does it matter which counting method to use?
Overall, since the counting method doesn’t affect the number of events that you receive or the conversion rate, it’s not so critical to pick the “right” setting. In most cases, you should be good to go with the default “Once per event” option. This is most relevant if you prepare some of the reports based on BigQuery, where any session or user metric needs to be calculated manually.
When you might consider using “Once per session” option?
- If you want to see the exact session count where conversion events occurred inside GA4 reports (default or custom). This would make sense for page_view conversions (e.g. when a specific page is viewed).
- If you are using Google Ads – For imported conversions you need to evaluate which counting method to use, especially when using automated bidding strategies. E.g. if you want to count specific page views as a conversion and use it in Google Ads, it would probably make sense to use “Once per session” option. In this case, if the same page is viewed multiple times during one visit – only 1 valuable action will be counted.
Hope you found it useful and let me know in the comments if you see any other potential use cases for different conversion counting methods in GA4.
