A Facebook lookalike audience is a group of new people Meta finds because they share characteristics with a source audience you already have, such as your customers, website visitors or Page fans. You need a source of at least 100 people, Meta recommends 1,000 to 5,000, and the people in your source are left out of the lookalike so you only reach new faces.
The catch to know about is Advantage+ lookalike. Meta switches it on automatically for new, duplicated and draft campaigns that use lookalikes built from website, mobile app or customer list audiences, and it lets Meta deliver your ads to people outside the lookalike when it expects better results. So the audience you picked is often a starting point, not a fence.
What you need before you create one
| Requirement | What Meta says |
|---|---|
| Minimum source size | At least 100 people |
| Recommended source size | Between 1,000 and 5,000 people |
| Lookalikes per source | Up to 500 from a single source |
| Source people | Excluded from the lookalike |
| Saved audiences | Can't be used as a source |
| From a custom audience | Admin or advertiser permission on the ad account |
| From a Page or Meta Pixel | Admin permission on that Page or Pixel |
| From an app | Administrator or developer of the app |
A source audience is simply the group the lookalike is based on. If you build a lookalike from your Page fans, your Page fans are the source. Meta's advice is that quality matters as much as size: a source made from your best customers can beat one that includes everyone who ever bought.
How to create a Facebook lookalike audience
- Open Audience in Meta Ads Manager. You can also do this inside ad set creation, under Audience.
- Select Create audience, then Lookalike audience.
- Choose your source, or select Create new source.
- Pick the audience size with the slider, and choose how many lookalike audiences you want.
- Select Create audience. You'll land back on Audience with the new lookalike listed.
One change matters if you're following an older tutorial: you no longer choose a location when you build the lookalike. Meta now uses the location settings of the ad set where you use it, so a new lookalike won't show an estimated size in Audience Manager. You'll see the size estimate once you add it to an ad set.
What the status column means
| Status | Meaning |
|---|---|
| Populating | Meta is matching your audience to profiles. This can take up to 3 days, and you can start ads straight away while it grows |
| Audience not created | Usually the source was too small |
| Ready | You can use it. You don't need to wait for refreshes |
Choosing the size slider
The slider sets how closely the new audience matches your source, as a share of the population in the ad set's location. Meta's rule is straightforward: smaller settings match your source more closely, larger settings give you a bigger and broader audience. You can also put several lookalikes into one ad set, and Meta will target people in any of them.
If you sell things with very different order values, look at a value-based lookalike. You build it from a customer list custom audience that includes a value column, so Meta can weight towards the customers worth most to you. Meta warns that very large files with lots of columns can time out in the browser, and suggests trimming rows with a zero value first.
Suggestion or hard limit
When you add a custom or lookalike audience under Suggest an audience, Meta treats it as a suggestion and may show your ads to other people when it thinks that'll improve performance. If you need the ads to stay inside the lookalike, Meta's steps are:
- In the ad set, find Suggest an audience and select Show settings.
- Select Further limit your audience, then Reach a limited audience.
- Add your lookalike there. You may need to untick Use as a suggestion.
When lookalikes are limited or blocked
- Special ad categories. Meta says lookalikes are limited or unavailable for some ads about financial products and services, employment or housing.
- Teen audiences. Targeting options are limited for audiences that include people under 18, or older in some countries.
- Flagged sources. If the custom audience behind your lookalike includes information Meta doesn't allow, such as specific health conditions or financial status, both can be flagged and can't be used in new campaigns. You fix the underlying custom audience first, or build a new one.
- Europe. Meta notes that privacy changes may affect campaigns reaching people in the European Region.
Lookalikes are only as good as the data feeding them, so make sure your pixel events are firing before you build one from website visitors. My walkthrough on setting up conversion tracking for Meta ads covers that part.
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My verdict
Build your first lookalike from your best customers, not your whole list, and keep the source in the 1,000 to 5,000 range Meta recommends. Then decide on purpose whether it's a suggestion or a limit, because Advantage+ will treat it as a suggestion unless you say otherwise. If you're new to the Ads Manager side of this, start with my Facebook ads guide for business owners.
Frequently asked questions
How many people do you need for a Facebook lookalike audience?
Meta needs a source of at least 100 people and generally recommends a source of between 1,000 and 5,000 people.
How long does a lookalike audience take to populate?
Meta says populating can take up to 3 days. You can start running ads with the audience straight away, and its size will grow as it populates.
Can I choose a country for my lookalike audience?
Not any more when you create it. Meta now uses the location settings of the ad set where you use the lookalike, so the estimated size appears in the ad set.
Why are my ads reaching people outside my lookalike audience?
Advantage+ lookalike is switched on automatically for many new campaigns and lets Meta deliver beyond your lookalike when it expects better performance. Use Further limit your audience if you need a hard limit.
Can I use a saved audience as a lookalike source?
No. Meta says saved audiences can't be used as a source for a lookalike audience.
