Why do Google Analytics reports display aggregated values in header that are not the sum of all rows?

Question

For my new Google Analytics API I am just doing some testing, if I am pulling the data correctly.

However, I encountered several confusing issues doin so. For example, when I look at my custom report, I tend to have a result for users ("Nutzer") that is not the sum of the affected rows, while for new users ("Neue Nutzer") it is exactly the sum of rows (=12.654):

Also when I am adding the dimension PagePath I am getting the same correct result for new users, but when I sum up the users, I am getting like 52.000 as a result for the same date range as above. How does this happen?

Answer 1

For each row in a report, the Total Users metrics in GA4 is the number of distinct users. Let's say the report is for the dimension Date and metric Total Users. One user could have visited your site on multiple dates. That users contributes +1 to the Total Users metric in multiple rows, but in the total, that user contributes +1 only once. GA4 uses Reporting identity to differentiate and de-duplicate users.

A user is only new during their first session. In this report, I believe each new user is only contributing +1 to one row. This allows the sum of the New Users rows to match the total.

Thanks,
Brett Sneed
The Google Analytics Team