Synchronization delay
Different measurement models
Consent and privacy settings
Minimum audience thresholds
Export filtering
Why your audience size can be smaller in Google Ads than in GA4
How to reduce audience size differences
Source

It is common to see a different number of users in your audience in GA4 (Google Analytics 4) compared to Google Ads. This discrepancy can be confusing, but it usually has logical explanations. This article explains why these differences occur, how the systems work behind the scenes, and what you should take into account.

Synchronization delay

It can take up to 24 hours for an audience created in GA4 to become available and populated in Google Ads. If you’re checking audience sizes shortly after creating or modifying an audience in GA4, expect a delay.

Different measurement models

GA4 uses an event-based tracking model and combines identity signals such as first-party cookies, device IDs, and Google Signals (if enabled). Google Ads, on the other hand, relies more heavily on cookies and ad identifiers.

This can lead to mismatches where users visible in GA4 are not recognized in Google Ads, especially when they use multiple devices or have blocked tracking.

Consent and privacy settings

Only users who have explicitly consented to personalized advertising can be included in audiences exported to Google Ads.

Users who decline consent may still appear in GA4 (anonymously or with limited data), but they are excluded from Google Ads audiences.

Minimum audience thresholds

Google Ads requires audiences to meet a minimum size before they can be used:

At least 100 active users for YouTube or Display Ads
At least 1,000 active users for Search Ads

Even if GA4 tracks a growing audience, it may not yet be usable in Ads until these thresholds are met.

Export filtering

Not all users who qualify in GA4 are exported to Google Ads. Export requires that the user:

Meets all audience conditions
Has given consent for ad personalization
Complies with Google Ads policies

This means the actual number of exported users is often smaller than the GA4 audience size.

Why your audience size can be smaller in Google Ads than in GA4

There are several reasons why your audience size may appear smaller in Google Ads compared to GA4:

Users without consent for personalized advertising are excluded from Google Ads audiences
Users may not be eligible for export due to policy restrictions or missing conditions
Audiences in Google Ads only start populating after they meet the minimum user threshold
A synchronization delay may temporarily cause GA4 to show more users than Google Ads
Technical limitations like cookie blocking, ad blockers, or browser restrictions can prevent user matching

Because of these combined factors, it is expected behavior that Google Ads often shows fewer users than GA4.

How to reduce audience size differences

Use a clear cookie banner that explicitly asks for consent for personalized ads and tracking. This increases the number of users eligible for export to Google Ads.

Enable Google Signals in GA4 to improve cross-device tracking and audience consistency.

Wait at least 24 hours after creating or modifying an audience in GA4 before evaluating its size in Google Ads.

Make sure your audience size exceeds the required minimum thresholds in Google Ads before trying to use it.

Source

Google Support: Why audience sizes differ between GA4 and Ads: https://support.google.com/analytics/answer/13656908?hl=en

Abisola

Meet Abisola! As the content manager at ClickPatrol, she’s the go-to expert on all things fake traffic. From bot clicks to ad fraud, Abisola knows how to spot, stop, and educate others about the sneaky tactics that inflate numbers but don’t bring real results.

View all posts by Abisola

Why is my audience size different in GA4 vs. Google Ads?

Table of Contents