Troubleshoot website custom audience size

The size of your custom audience may decrease because it may not include some iOS 14 users. Learn how iOS 14 may affect your ad strategy.

A website custom audience allows you to show your ads to people who have visited your website. However, not all visitors are included in your final website custom audience size. This is also true for the number of Meta pixel fires.

Note: How soon you can start using your website custom audience depends on your website traffic and when you placed your Meta pixel.

• Website visitors must also be Meta technologies users for their visits to count. However, we don't include accounts that have opted out of online behavioural advertising.

• Pixel fires aren't equal to unique visitors. A single visitor may fire multiple pixel events, but the visitor will only be counted one time. This is also true when a unique visitor engages in multiple events (such as adding an item to their basket, adding payment information and purchasing) or if a web page has a pixel installed multiple times. (To compare your unique visitors and page views, you can go to your website's management dashboard.)
  
  This is intentional, as firing the pixel on every page allows you to build audiences and website events based on specific pages that people visit.

• Reporting may differ between Meta technologies tools and third-party analytics. Sometimes, advertisers may use multiple tools to assess audience size, pixel fires, events, visitors or performance. Remember that each system has its own measurement system, and you may notice discrepancies between them. You shouldn't expect numbers to perfectly line up between different platforms. Typically, third-party analytics tools can help you understand your website activity, whereas Meta Ads Manager reporting can help you build the right types of custom audiences to connect with your customers.

  • Fires: Facebook Analytics measures the total number of unique visitors, regardless of profile match rates or whether an account has opted out of advertising permissions. Events Manager measures pixel fires, regardless of the number of unique visitors.
    
    Meanwhile, third-party analytics may measure visitors rather than unique visitors or the relationship between visitors and pixel fires. For example, imagine that your third-party analytics tool reports that your website has 20,000 visitors and those visitors viewed 7 pages on average. Given that one visitor can cause multiple pixel fires and multiple events can fire on the same page, you can expect about 140,000 pixel fires or more for a single page (20,000 visitors multiplied by 7 page views equals 140,000 fires per page). However, your website custom audience only considers unique visitors, so your audience size may be closer to 3,000 unique visitors (20,000 visitors divided by 7 views equals 2,857 unique visitors).

• Sessions vs visitors: Third-party analytics tools may count unique sessions rather than unique visitors. For example, a single visitor may view your website first on their phone and then on their desktop computer. That would be two unique sessions, but only one unique visitor. This is also true if a single user erases cookies or refreshes a page.

• Measurement timeframes: Meta technologies tools count all the time, whereas third-party analytics may count unique visitors and sessions using different periods of time.

• Waiting until you have several hundred people in your website custom audience before using it.
• Using fewer conditions or selecting Anyone who visits your website to include the maximum number of people possible.
• Increasing your audience window from the default 30 days to 180 days.