It’s common to encounter disparities in conversion metrics when comparing Google Analytics 4 (GA4) with Universal Analytics (UA). These variations can often leave businesses scratching their heads, wondering why the numbers don’t align. To shed light on this issue, we’ll delve into the most prevalent causes of data discrepancies and provide actionable steps to rectify them.

1. Conversion Window Settings

   The conversion window settings in Google Ads define how long after a user interacts with a Google Ads touchpoint that conversion credit can be attributed to that interaction. The difference in these settings between UA and GA4 can lead to varying conversion attributions. For example, you may set 30 days in a Google Ads conversion goal linked with UA and 45 days in a Google Ads conversion goal linked with GA4.

   Ensure that the conversion window settings in Google Ads for UA conversion actions match those set for GA4 conversions within the GA4 property settings (e.g. both are 30 days). Alignment in this aspect can help mitigate conversion discrepancies.

2. Variances in Conversion Counting

   UA counts one goal conversion per session, whereas GA4 often counts one conversion per event. For example, if a user submits calls to the same website phone number in one session, the two website phone calls will be counted as one conversion in UA and two conversions in GA4.

3. Attribution Model Differences

   Attribution models dictate how credit is assigned to different touchpoints within a conversion path. The utilization of different attribution models can lead to varying credit allocations across campaigns, affecting the overall conversion count.

   To reduce conversion discrepancies, verify that the attribution models for GA4 conversions are consistent with those used for UA conversions in the conversion summary.

4. Auto-Tagging and Data Collection

   The firing conditions of tags can impact when and how tags are triggered. If data collection is restricted in UA but not in GA4, counts of users, sessions, page views, and conversions can be higher in GA4.

   The recommended approach is to rely on gtag.js or gtm.js (using GA4 tags) for data collection in GA4 properties. After tag implementation, ensure tag firing conditions align to avoid discrepancies.

5. Site Coverage Discrepancies

   Measurement gaps can arise if the UA tag is implemented on a different set of pages compared to the GA4 tag. This is particularly relevant when a landing page from a Google Ads ad lacks accurate tagging. Differences in tag implementation across pages can lead to disparities in user, session, page view, and conversion counts.

   To minimize discrepancies, adopt consistent tag implementation methods for UA and GA4, such as Google Tag or Google Tag Manager. Review past settings, including cross-domain tracking, and confirm tag implementation using the “Tag coverage” summary.

Understanding the reasons behind conversion discrepancies between GA4 and UA is essential for accurate data analysis and decision-making. By addressing the factors outlined above and aligning your settings, you can achieve a more harmonized view of your conversion metrics. As the digital landscape evolves, ensuring the integrity of your analytics data is key to driving success in the online world.