Quick answer: A lookalike audience (sometimes called "Similar Audiences" in Google Ads) is a group of users that ad platforms identify as behaving similarly to a source audience you provide. Upload your customer list, and Meta or Google find new users with matching characteristics. Lookalike audiences are one of the most reliable ways to scale paid acquisition beyond people who already know your brand.
How Lookalike Audiences Work
The platform analyses your source audience for shared signals: demographics, interests, online behaviour patterns, content engagement, and purchase patterns where data is available. It then identifies new users sharing those signals.
Lookalikes are sized by similarity. Meta’s 1% lookalike is the closest match to your source audience (smallest, highest similarity). 5%, 10% lookalikes scale wider but with less similarity. Google’s Similar Audiences work on the same principle without explicit size tiers.
Best Source Audiences for Lookalikes
- Existing customers (especially high-value or repeat customers).
- High-intent website visitors (cart abandoners, demo requests, multiple-page visitors).
- Email subscribers who have opened or clicked within the last 90 days.
- Recent converters (last 30-90 days, weighted toward recent for relevance).
The quality of your source audience determines the quality of the lookalike. A list of 100 best customers usually outperforms a list of 10,000 mixed-quality leads.
Frequently Asked Questions
How big should my source audience be?
Meta requires at least 100 people for a lookalike but recommends 1,000-50,000 for best results. Google Similar Audiences also work better with larger source audiences. Aim for at least 500 high-quality source records.
Are lookalike audiences still effective in 2026?
Yes, with caveats. Apple's privacy changes and third-party cookie deprecation have reduced lookalike accuracy. The most effective lookalikes now come from first-party data (your own customer list) rather than pixel-based behaviour.
Can I use lookalikes for B2B targeting?
Yes. Lookalikes work for B2B, especially when your source audience is buyers (decision-makers in the right ICP). LinkedIn lookalikes are particularly strong for B2B because they target by professional attributes.
What is the difference between lookalike audiences and Customer Match?
Customer Match targets your existing customers directly (you upload a list, Meta or Google match it to user accounts). Lookalike audiences target new users similar to those existing customers. Use both: Customer Match for retention and reactivation, lookalikes for acquisition.
Take this further
Lookalike audiences are one of the cleanest scaling levers in paid acquisition when set up properly. We help clients build first-party data assets that produce strong lookalikes.
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