What Is the "Unknown" Audience Segment in Facebook Ads?

When getting into the nitty-gritty of your Facebook ads reporting in Meta Ads Manager, you might notice something curious: a portion of your audience being classified as "Unknown." It’s enough to make any advertiser raise an eyebrow and wonder, “Who—or what—is this audience?”

If this sounds like you, don’t worry. Let’s break down the "Unknown" audience, why it appears, and how to navigate this anomaly like a pro.

What is the "Unknown" audience in Facebook ads?

The "Unknown" audience segment refers to a category of users that Meta’s algorithm couldn’t classify into these standard audience segments:

Engaged audiences include people interacting with your content or ads while existing customers have already converted. New audiences encompass anyone who doesn't fit into these two groups.

Occasionally, you might encounter the mysterious "Unknown" audience segment, as seen in this ad example:

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This “Unknown” audience can happen for several reasons:

• Limited data: The algorithm might lack sufficient information about these users' behaviors or interactions, preventing accurate categorization. That often happens when the users haven't engaged enough with content or ads for the system to recognize patterns.
• Audience segment not yet defined: “Unknown” may reflect that Meta delivered ads to people before they defined your audience segments. One source has reported experiencing results initially categorized as "Unknown," which Meta later reassigned to one of the defined audience segments over time. As more interactions and behaviors are tracked, the system gathers sufficient data to reassess and reclassify users from the "Unknown" category to more defined audience segments.

• Privacy settings: Users who have enabled strict privacy settings can have their data anonymized, which makes it challenging for Meta's algorithm to gather the necessary Facebook audience insights to classify them into specific segments. 
• Algorithmic oversight: Despite Meta's sophisticated AI, it can occasionally miss or misinterpret data due to technical limitations or errors in data processing. This results in users being categorized under the "Unknown" segment, essentially falling through the cracks of the usual audience segmentation process.
• New users: These are users who have recently joined Facebook or have only recently begun engaging with specific content, making them harder to target based on past behavior. Since these users haven't yet developed clear interaction patterns, the algorithm struggles to classify them accurately into predefined segments.
• Anomalous behavior: Users who exhibit behavior that doesn’t fit into any existing targeting category, making them difficult to reach through typical ad campaigns. These users may have unique or unpredictable behaviors that don't align with standard audience definitions, leading to their inclusion in the "Unknown" segment. For example, the users who engage sporadically with diverse content—liking a gardening post one day and an extreme sports post the next—without showing a consistent pattern. This unpredictability makes their interests hard to categorize.

🔔 Facebook Ads Manager classifies users as "Uncategorized" when it hasn't yet assigned them to a specific category because there isn't enough data on their behaviors or interactions to classify them accurately. While "Uncategorized" users have the potential to be classified as more data is collected, "Unknown" users sometimes stay in that segment because of users' privacy settings.

Why does the "Unknown" audience matter?

At first glance, it might feel like the "Unknown" audience is just a random pool of users. But it can have a significant impact on your campaigns:

If a sizable chunk of your budget goes to the "Unknown" audience, it might limit your ability to optimize spending for well-defined audience groups. That can lead to inefficiencies in your ad spend, as you may not reach the most relevant and high-converting audiences. Instead of investing in known, high-potential segments, you may use resources on less likely users to engage or convert.

It can create confusion when analyzing results, as you might struggle to identify what’s driving performance. Without clear insights into the "Unknown" audience, it becomes challenging to pinpoint which factors are contributing to your campaign's success or failure. This lack of clarity can hinder your ability to make informed decisions, adjust your strategy, and improve future campaigns.

But it’s not all bad news…

Because these users are more challenging to categorize, fewer advertisers may target them. This can result in lower competition and lower costs per click (CPC) or cost per acquisition (CPA). Thus, targeting this segment might result in better ROI, as there is less competition for their attention.

These unknown audience segments might include users not exposed to your brand, making them an untapped market.

How to approach the "Unknown" audience segment

Before getting into strategies, knowing how to view the "Unknown" audience data in Meta Ads Manager is essential.

In Ads Manager, navigate to Breakdowns > By Demographics > Audience Segments

Once you’ve located the data, here’s how you can make the most of this mysterious segment:

1. Review audience segments in reporting

Use Meta Ads Manager's Breakdown by Audience Segments feature to:

• Analyze performance: Examine key metrics like engagement, conversion rates, and cost per result to assess overall campaign performance. Identify if specific campaigns or ad sets are underperforming, which might be due to targeting a significant "Unknown" audience or less-defined segments.
• Adjust targeting: By seeing how many users fall into the "Unknown" category, you can gauge how much of your audience isn't well-defined. That signals the need to tighten your targeting criteria to ensure your ads reach more specific and relevant segments, optimizing your budget allocation.

2. Optimize for better data

If a significant portion of your audience is classified as "Unknown," you must refine your campaigns to gather more precise audience signals. Here's how:

• Use custom audiences for more precise targeting
  Facebook custom audiences let you target users familiar with your brand, such as website visitors or email subscribers. By focusing on these audiences, you reduce reliance on Meta’s algorithm to identify and categorize undefined users, minimizing the size of the "Unknown" segment.
• Retarget users based on their interactions
  The "Unknown" segment might include individuals who have shown interest in your product or service but haven't engaged enough for Meta to categorize them accurately. You can provide more precise behavioral signals by running Facebook retargeting ads based on their interactions with your social media advertising platforms, website, and app. That helps Meta’s algorithm better classify these users, gradually reducing the size of the "Unknown" audience.
• Experiment with interest-based targeting

As mentioned, unknown audiences can exhibit anomalous behaviors and lack apparent common interests. Testing different interest-based targeting strategies can help you identify potential subgroups within this category.

Why does this happen in Advantage+ Campaigns?

If you’re using Advantage+ Shopping campaigns, you’ve likely seen more of your budget allocated to "Unknown" audiences. That is because ASCs rely heavily on Meta’s algorithm to identify potential customers—sometimes casting a wider net than manual campaigns.

Advantage+ campaigns aim for efficiency by automating targeting, but they’re not infallible. Regularly reviewing audience reports and testing manual setups alongside ASCs can help you strike the right balance.

Final thoughts: Should you worry about the "Unknown"?

The "Unknown" audience segment might seem mysterious, but it’s often just a byproduct of Meta’s push for privacy and automation. While monitoring its impact on your campaigns is essential, it’s equally important not to overthink it.

By refining your Facebook ad targeting strategy, testing manual approaches, and using tools like custom audiences, you can minimize the "Unknown" segment and direct your budget toward the people most likely to convert.

Audience segments don’t have to stay a mystery 🕵️

Madgicx’s Targeting Insights tool, part of the comprehensive 360° Meta Audit, empowers you to discover hidden audience opportunities and optimize your campaigns with precision. It analyzes key metrics like ROAS, Revenue, Amount Spent, and Cost per Purchase, breaking down performance by funnel stage—acquisition prospecting, acquisition re-engagement, retargeting, or retention.

By identifying high-performing audience groups and eliminating underperformers, you’ll unlock the potential of untapped segments and maximize your budget efficiency. 

Try Madgicx for free today and make every audience work for you!

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