A Facebook custom audience is an audience you build from your own data, like website visitors or a customer list, or from people who've engaged with you on Facebook, Instagram, WhatsApp or Threads. You use it to retarget people who already know you, to exclude existing customers, or as the source for a lookalike. Meta allows up to 500 custom audiences per ad account.
The detail worth knowing: a customer list custom audience shows as Outdated once it hasn't been updated in over 30 days, and Meta says that may affect delivery. Engagement audiences are the opposite. They refresh constantly, so you only rebuild them when you want a different time window or engagement type.
The custom audience types Meta offers
Meta splits custom audiences into two families: people who interacted with your business, and people who interacted with your content on Meta's apps.
| Type | Who it targets |
|---|---|
| Website | People who visited your site, tracked through the Meta Pixel |
| App activity | People who took specific actions in your mobile app |
| Catalog | People who interacted with items in your product catalog |
| Customer list | Customers whose emails or phone numbers you upload to match |
| Offline activity | People who bought in store or interacted offline |
| Video | People who watched your videos on Meta platforms |
| Lead form | People who opened or submitted a lead form on your ads |
| Instant Experience | People who interacted with your full-screen Instant Experience ads |
| Shopping | People who browsed or bought from your Facebook or Instagram Shop |
| Instagram account | People who interacted with your Instagram business account |
| Events | People who responded to your Facebook Events |
| Facebook Page | People who interacted with your Facebook Page |
| On-Facebook listings | People who interacted with your Facebook Marketplace listings |
| Exclusion-only | A customer list you can only use to exclude people |
How a customer list audience is matched
You upload identifiers you've collected, such as email, phone number and address. Meta hashes that information before use, then matches the hashed data with profiles on its apps so you can advertise to those customers on Facebook, Instagram and Meta Audience Network. Meta says it doesn't learn any new identifying information about your customers from hashed data.
The more identifiers you include, the better the match. Meta's Match score column gives a score out of ten, shown in steps of 0.5, worked out by dividing matched rows by uploaded rows. If you match on mobile advertiser ID, Meta suggests adding email, phone number, first name or last name to help, because iOS changes can lower match rates.
How to use a custom audience in an ad set
- Wait until the audience shows Ready under Status in Audience.
- Create your ad set and find Suggest an audience, then Show settings.
- Select Include these custom audiences and search for yours, or create a new one.
- To keep delivery inside the audience, use Further limit your audience and Reach a limited audience, and untick Use as a suggestion if you see it.
- To keep customers out of a new-customer campaign, add them as an exclusion instead.
Without step 4, Meta treats your custom audience as a suggestion and may show ads to other people when it expects better results.
Engagement audiences and the time window
An engagement audience uses actions taken across Meta's apps, like watching a video, following a Page or opening a lead form. A website audience uses actions on your own site, which Meta calls events. When you build an engagement audience you choose how many days to include. Meta's example: pick 30 days, and someone who engaged 29 days ago is in, then drops out the next day unless they engage again.
One trap: if a Facebook Page is deleted, audiences based on it can't be used in new ad sets or other campaigns, and that includes lookalikes built from them.
Website audiences: three uses Meta suggests
- Retargeting people who visited in the last 30 days but haven't converted.
- Prospecting by using visitors as a base for finding similar new customers.
- Upselling and cross-selling to people who've already bought on your site.
All three depend on the pixel recording the right events. If yours isn't set up yet, follow my guide to conversion tracking for Meta ads before you build anything.
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What gets an audience flagged
Meta checks that audiences don't carry information its terms don't allow, and gives specific health conditions and financial status as examples. A flagged audience can't be used in new campaigns, and Meta recommends editing or pausing any live campaign using one. You can remove the problem data, build a new audience, or request a review in Ads Manager or Audience Manager if you think the flag is wrong. Meta also limits targeting for audiences that include people under 18.
My verdict
Start with three: website visitors, a customer list to exclude buyers from acquisition ads, and a video or Page engagement audience for warm retargeting. Put a monthly reminder in to refresh the customer list so it never goes Outdated. When you're ready to find new people, use your best custom audience as a lookalike source. For ad ideas to show these warm audiences, my breakdown of good Facebook ads is a useful start.
Frequently asked questions
How many custom audiences can you have on Facebook?
Meta says you can create up to 500 custom audiences per ad account.
Why does my custom audience say Outdated?
Meta shows Outdated when a customer list hasn't been updated in over 30 days, which may affect ad delivery. Choose Update list to refresh it.
Does Meta see my customers' emails?
Meta hashes the identifiers before use and matches the hashed data to profiles. It says it doesn't learn new identifying information about your customers from hashed data.
Do engagement custom audiences update by themselves?
Yes. Meta says engagement custom audiences refresh constantly, so you only need to edit them to change the time period or engagement type.
Can I use a custom audience to exclude people?
Yes. You can exclude an audience from an ad set, and Meta also offers exclusion-only customer list audiences that can only be used for exclusion.
