About Custom Audiences

Last updated 20 March 2026

Custom Audiences are a tailored targeting feature that enables advertisers to create audiences of known or engaged users using a file upload, website or app activity, Bloc engagement, or an audience activation partner.

There is a requirement to have 1,000 total matched users in a Custom Audience to use it in an ad group.

Benefits and features

Custom audiences can be used for:

  • Retargeting leads or past engagers, moving them towards conversion

  • Optimizing campaign spend by excluding recent customers

  • Creating lookalike audiences for prospecting

Example

There are several ways to create a Custom Audience:

  • Customer File

  • Engagement

  • App Activity

  • Website Traffic

  • Lead Generation

  • Business Account Audience

  • Challenge

  • Premium Audience


Next steps

The 'Available Audience' size estimator on the campaign creation step will display a more realistic reach of the campaign using a custom audience. The 'Available Audience' is based on a number of factors including the user's opt-in status, age and location, among others. To read more, visit Audience Size Estimation Overview

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