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Difference between GA4 and Backend data

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Have you ever noticed that the data generated from your website, such as the number of transactions or leads, does not always match when you view it in Google Analytics 4 (GA4) reports compared to reports from the backend system of your application?

This discrepancy is a common problem in the world of web analytics, and understanding its causes and how to address them is essential to making informed decisions.

Understanding the fundamental difference

To understand why data differs between GA4 and the backend, it is essential to recognize the fundamental difference in the goals and methodologies of these two tools. GA4 is an analytics and projections platform, while the backend is the system that records each and every transaction and event without exception. This fundamental distinction creates the basis for the discrepancies we often encounter.

Variation within an acceptable range

It is important to note that not all differences are cause for alarm. In many cases, a variance of GA4 data compared to the backend that is within the range of 1% to 10% is considered normal and should not cause much concern. This variability can be attributed to various technical and user behavioral reasons, and is still within an acceptable range for analysis and projections.

Discrepancy scenarios and their solutions

  1. Changes to the conversion path
If you see a significant discrepancy in data between GA4 and the backend, one of the possible scenarios is a change in the conversion path on your website. This can occur when you add or modify the path (URL) through which users complete transactions. If sending the “purchase” event to GA4 depends on this path, GA4 may not log these transactions correctly. Solution: To address this issue, it is recommended to reconfigure the triggers used in Google Tag Manager (GTM) and redefine the variables that should be captured. It is crucial to ensure that GA4 is configured to follow the new conversion path.
  1. Hit limit per session in GA4
A lesser known aspect is the 500 events per session limit in GA4. If a user exceeds this limit, additional events will not be registered in GA4. Although this scenario is unlikely on most websites, it can occur, for example, if your company has a sales assistant who processes multiple purchases in a single session. Solution: To work around this limitation, it is important to monitor and, if necessary, redistribute events in GA4 to ensure they are logged properly.
  1. Blocking of cookies by users
Users may intentionally block cookies or use ad blocking extensions, which may impact GA4’s ability to track events. Solution: Although GA4 cannot retrieve this information, it is possible to detect if users are blocking cookies using JavaScript scripts and report this as an event in GA4. This way you can at least get an idea of ​​the percentage of sessions affected by cookie blocking.
  1. Interrupts before GA4 tag is triggered
This situation occurs when users leave a page before it fully loads or before the GA4 tag is activated. It can also occur if users close the page before GA4 has a chance to log the event. Solution: Ensure that the GA4 or GTM code is placed correctly on the website, preferably immediately after the <head> tag to ensure it fires before users leave the page.
  1. JavaScript errors
GA4 uses JavaScript-based tracking code, and this code may stop working if the users disable JavaScript in their browsers or if JavaScript errors occur on the page. Solution: It is essential to ensure that the GA4 tracking code is implemented correctly and that there are no JavaScript errors on the page. This will guarantee that events are recorded effectively.
  1. Data sampling in GA4
When dealing with large amounts of data, GA4 uses sampling as a technique to process and report more quickly. However, this can lead to the loss of accurate data, especially when dealing with large volumes of information. Solution: Monitor GA4 reports to identify when data sampling is being applied and, if necessary, consider using unsampled report views in GA4 for more accurate data.


Data discrepancy between GA4 and the backend is a reality that many digital marketing professionals and data analysts must address. Understanding the potential causes of these discrepancies and taking proactive steps to resolve them is critical to gaining an accurate view of online activities and making decisions based on solid data. By implementing the solutions mentioned above and constantly monitoring data quality, you can minimize differences and trust the insights you get from both sources of information.