Why does my RPM look different with GA4?

Miriam Tremelling

September 09, 2023 14:53

Once your Raptive dashboard is running Google Analytics 4, you may notice a slight difference in your RPM. This is due to how GA4 counts sessions and has no impact on earnings.

Sessions tend to be higher in GA4 than in Universal Analytics, which affects RPM calculations. We use earnings and sessions to calculate RPM, so if sessions are higher and earnings remain the same, RPM is lower.

Here’s how RPM is calculated:

(Total ad earnings divided by sessions) multiplied by 1,000 = RPM

Let’s look at an example from an imaginary site that earned $15,000 from ad revenue in the last 30 days. Universal Analytics counted 500,000 sessions during that time frame.

($15,000 / 500,000)* 1000 = $30 RPM

Because of the way GA4 tracks sessions, this site might be showing 525,000 sessions for the same time period in GA4. So earnings are the same, but RPM has changed:

($15,000 / 525,000)* 1000 = $28.57 RPM

The difference in session count between UA and GA4 varies from site to site—some creators may see a higher number of sessions, while others may see a lower number. In addition, pageviews and sessions for AMP traffic aren’t tracked in GA4.

The most important thing to remember is that the lower RPMs you may see in GA4 have no impact on your revenue. The lower RPM has to do with how GA4 counts sessions, and we use earnings and sessions to calculate RPM (not sessions and RPM to calculate earnings).

Why are sessions different in GA4?

Google defines sessions as a period of time during which a visitor interacts with your website or app. Google Analytics 4 session metrics are derived from the session_start event, an automatically collected event. GA4 relies on a statistical estimate of sessions by estimating the number of unique session IDs, while UA did not estimate the number of sessions. The result is a more efficient, accurate session count with GA4.

The table below shows how Google defines sessions in UA vs. GA4.

*Note: In your Raptive Dashboard, we are using the session_start metric to count sessions. We’ve found session_start data to be more closely aligned with Universal Analytics data. In the GA4 UI, your session_start total by day is easily found in the Engagement > Events report.

Session
UA	GA4
Period of time a user is actively engaged with your website or app Has defined parameters for what may cause it to end e.g. a session will end when there has been more than a 30-minute period of inactivity (depending on the session timeout settings), the timestamp has been cut off at midnight (according to the timezone the view is set up in), or new campaign parameters are encountered. If a user comes back after a session timeout, it will start a new session If the user is on the website when midnight arrives, a new session will be started If a user picks up new campaign parameters while on the website, a new session will be started	aka Session Start To determine the session that each event comes from, the session_start event generates a session ID and Analytics associates the session ID with each subsequent event in the session A session will end when there has been more than a 30-minute period of inactivity (depending on the session timeout settings) Sessions are not restarted at midnight or when new campaign parameters are encountered If a user comes back after a session timeout, it will start a new session

Google has compiled a list of potential factors to explain why sessions are often higher in GA4. These include:

Filters: The data in UA reporting may be subject to view filters that exclude data
Sessions are not restarted at midnight or when new campaign parameters are encountered
Late hits: GA4 processes events that arrive up to 72 hours late, while UA only processed late hits that arrived within 4 hours of a day’s close.

We’ll continue to monitor and update you on how GA4 affects your data and you can be assured your Raptive dashboard has the most accurate information available. Please reach out to support@raptive.com with any questions.