A lookalike audience is a Meta audience of new people who share characteristics with a source audience you provide, usually a custom audience of customers or good leads (Meta Business Help Center). Meta uses information such as demographics, interests and behaviors from the source to find similar people, and you choose how close the match is with a percentage.
How a lookalike audience works today
Meta’s create article sets the rules:
| Setting | Rule as Meta documents it |
|---|---|
| Source size | at least 100 people; 1,000 to 5,000 recommended |
| Lookalikes per source | up to 500 |
| Audience size | 1% to 10% of the population of your ad set’s locations |
| Location | taken from the ad set, no longer chosen at creation |
| Populating | up to 3 days; ads can run meanwhile |
| People in the source | excluded from the lookalike |
| Saved audience as source | not allowed |
The 1% to 10% range, with 1% as the closest match, is spelled out in Meta’s Leads Center article. The location change has a visible side effect: new lookalikes show no estimated size in Audience Manager until you use them in an ad set. Add several lookalikes to one ad set and Meta targets people in any of them.
Lookalike audiences and Advantage+ audience
Advantage+ lookalike lets Meta deliver to people outside your lookalike when that’s likely to improve performance. Meta switches it on automatically for new, duplicated and draft ad sets that use lookalikes built from app, website or customer list custom audiences (About Advantage+ lookalike).
In Sales, App promotion and Leads campaigns, lookalikes go under Custom audience inclusions in Add suggestions, which makes them suggestions in Advantage+ audience. To make one a hard limit, choose Further limit the reach of your ads, select it again and uncheck Use as a suggestion (use custom or lookalike audiences). And you can’t exclude a lookalike while Advantage+ audience is on (Advantage+ audience setup).
The practical upshot: a 1% lookalike added as a suggestion is a hint, not a fence. If you want to know whether the lookalike itself works, make it a control in at least one arm of the test.
Where lookalikes are limited or unavailable
- Special ad categories. For housing, employment and financial products and services campaigns from US-based advertisers, or reaching the US, Canada or certain European countries, Meta lists lookalike audiences as limited or unavailable, and Advantage+ lookalike as unavailable (Meta Business Help Center). Meta’s special ad categories covers the other rules.
- Flagged sources. If the custom audience behind a lookalike is flagged for information Meta’s terms don’t allow, the lookalike is flagged too, and the fix starts at the source (restrictions on certain custom audiences).
A lookalike built from leads that never qualified finds more people like them, so judge it on the leads it brings. DropCPL computes CPL for every creative × landing page combination from first-party leads and spend synced per ad from the Meta Ads API. Start free →
Lookalike audiences in lead generation
The source decides what Meta looks for. Meta’s own advice is that a source made of your best customers can beat one that includes all of them. In lead gen, that means seeding from leads that qualified or closed, not from every form fill.
Example: you have 2,000 leads, and 300 of them qualified. A lookalike of all 2,000 teaches Meta what a form filler looks like. A lookalike of the 300 teaches it what a qualified lead looks like, and 300 clears Meta’s 100-person minimum. Meta’s Leads Center can also build custom and lookalike audiences straight from your leads once you’ve generated more than 20 on Meta.
Which leads qualified is decided in your CRM. DropCPL doesn’t qualify leads: it forwards each landing page lead to your CRM by webhook, with its ad and landing page attached, so the CRM has what it needs to build that list.
Related terms
- Custom audience: the source of every lookalike
- Advantage+ audience: where lookalikes become suggestions
- Conversion leads optimization: the other way to point Meta at qualified leads
- Cost per result: the number to look past when you judge an audience