Why the audiences size in GA4 and Google Ads is different

Short answer

The difference in audience size between GA4 and Google Ads is often due to differences in user identification methods, data processing, privacy settings, and audience eligibility criteria between the two platforms.

Detailed answer

The differences in audience size between GA4 and Google Ads can be attributed to various factors outlined in the official documentation. Here’s an elaborated explanation addressing this issue:

1. Ads Personalization Preferences:
   In GA4, audience size represents all users meeting the criteria. In Google Ads, it reflects only the remarketable portion due to ads personalization preferences set by both GA4 users and end-users. For example, a single user can be measured in Google Analytics 4, but if the user has declined ads personalization in Google may not be remarketable; this specific user will be counted in GA4, but won’t be visible in Google Ads.
2. Google Analytics Settings: Depending on the specific settings applied to your GA4 property this difference in audience size might change.
   • Google Signals: Necessary for exporting audiences to Google Ads. If it’s turned off, the corresponding data isn’t included in exported audiences but is included in GA4 reports.
   • Regional Settings: Turning off Google signals in certain regions excludes data from those regions in exported audiences. Making the difference bigger.
   • Property Settings: Personalized advertising settings at the property level and for specific events/user-properties can impact the data exported.
   • Tag Configuration: Adjustments in Google Analytics tagging can opt out of using Analytics data for Ads personalization.
   • Ads Personalization for Linked Google Ads Account: This needs to be enabled for audience export to Google Ads.
3. End-User Settings: Users can change the way Google Ads advertising works for them, changing the way ads works in some scenarios.
   • Google Account Configuration: Users’ Google Account ads personalization settings impact data collection.
   • Operating System-Level Settings: Older Android versions allow users to limit personalized advertising data collection.
   • Consent Mode: Users opting out of ads data storage via consent banners impact audience eligibility for remarketing.
   • ATT Consent: Apple’s App Tracking Transparency policy affects remarketing eligibility if users deny consent.
4. Additional Reasons for Differences:
   • Backfilled Audiences: Newly created audiences in GA4 are backfilled in Google Ads but may not immediately reflect in GA4 reports.
   • Data Freshness: Time lags in data collection and processing between Analytics and Google Ads can cause temporary discrepancies.
5. Areas of Discrepancies:
   • Export to Google Ads: Only includes users from the audience creation time forward, plus backfilled users.
   • Analytics Reporting: Shows all users for the lifetime of the property.
   • Audiences Management Table and Reports: Counts only include users from the audience creation date forward, excluding backfilled users.
   • Audience Estimates in Builder: Estimates based on the last 30 days’ data, which may not align with the exported audience size.

How to improve audience size in Google Ads

Reducing the difference in audience size between GA4 and Google Ads can be challenging due to inherent differences in how each platform processes and counts users. However, there are strategies you can employ to minimize this discrepancy:

1. Harmonize Ads Personalization Settings:
   • Align ads personalization settings across Google Analytics and Google Ads.
   • Check and adjust property-level settings and tag configurations in GA4 to ensure consistent data usage for ads personalization.
2. Enhance User Consent Management:
   • Implement a user-friendly consent management platform to maximize opt-ins for ads personalization and analytics data collection.
   • Clearly communicate the value of data sharing and personalization to users to encourage consent.
3. Audit Audience Definitions:
   • Regularly review and align audience definitions in both GA4 and Google Ads to ensure they are based on similar criteria and behaviors.
   • Utilize GA4’s advanced segmentation capabilities to create more targeted audiences that are likely to be eligible for remarketing in Google Ads.
4. Educate End-Users:
   • Inform your website or app users about the benefits of personalized ads and the impact of their privacy settings on the ads they see.
   • Provide clear options for users to adjust their personalization and privacy settings.
5. Utilize First-Party Data:
   • Strengthen your first-party data collection strategies to build robust audience profiles.
   • Encourage user account creation and engagement to gather more comprehensive data.
6. Stay Updated with Platform Changes:
   • Keep abreast of any updates or changes in GA4 and Google Ads that might affect audience data processing.
   • Adjust your settings and strategies in response to new features or privacy regulations.

In conclusion, the variation in audience sizes is influenced by multiple factors such as user consent, Google signals status, regional settings, and the inherent differences in how GA4 and Google Ads define and count users. These discrepancies are expected and reflect the complex nature of data tracking and user privacy across different Google platforms. Understanding these nuances can help in aligning marketing strategies and expectations between GA4 and Google Ads.