Why Facebook Is Hiding Audience Size
Facebook has temporarily disabled reach estimation for certain types of Custom Audiences due to a technical and privacy-related issue. According to Facebook, allowing size estimates for these audiences could potentially lead to misuse of the tool.
Because of this, Facebook is withholding audience size information, even though the audiences are still being built and are fully usable.
Official Explanation from Facebook Support
Facebook Support has confirmed the following:
“We identified a technical issue with reach estimation for Custom Audiences that could potentially allow misuse of the tool.
We’re temporarily removing the ability to see reach estimates via the API for the following Custom Audience types:
Custom Audiences from a customer data file
Offline conversions Custom Audiences
Website Custom Audiences that use Advanced Matching
Mobile App Custom Audiences that use Advanced Matching
You will still be able to create new Custom Audiences and use them for ads targeting.
Ads delivery and reporting will remain unaffected by this change.
We are currently investigating solutions to restore these reach estimates.”
What “Not Available”, “-1”, or “20” Actually Means
These values do not represent the real audience size.
They simply indicate that:
Facebook is not displaying the size
The audience is still collecting users
The audience is active and usable
As long as the status shows “Ready”, the audience is functioning correctly.
Are These Audiences Still Usable?
Yes. Even when the audience size is hidden:
✅ Custom Audiences can be used for ad targeting
✅ They can be used as source audiences for Lookalike Audiences
✅ Ad delivery is not affected
✅ Reporting remains accurate
This is a display limitation only, not a tracking or performance issue.
When Should You Be Concerned?
You should investigate further only if:
The audience status shows Error
The audience remains in Populating for an unusually long time
No events are being tracked at all
If the status is Ready, the audience is good to use.
Why Facebook Did This
Facebook disabled audience size estimates temporarily because:
There were potential errors in reach estimation
Audience size visibility could be misused
Accuracy and privacy needed to be protected
Facebook has confirmed this is temporary, while they work on a long-term solution.
Workarounds to Gauge Audience Scale
While Facebook does not show exact sizes, you can:
Create a Lookalike Audience from the Custom Audience
Launch a campaign and monitor reach and delivery
Use performance data to understand scale instead of size estimates
Key Takeaways
“Not Available”, “-1”, “Below 1,000”, or “20” is normal behavior
Facebook intentionally hides size estimates for certain Custom Audiences
Your audiences still work for targeting and Lookalikes
Ads delivery and reporting are not impacted
A Ready status means the audience is usable
Official Facebook Documentation
For Facebook’s official explanation, refer to this article:
https://www.facebook.com/business/help/1523083297982009?id=2469097953376494
If you need help confirming whether your Custom Audience is set up correctly or want guidance on best practices, feel free to reach out.