What Is a Lookalike Audience and How Does It Work?

A lookalike audience is a targeting feature offered by advertising platforms — most notably Meta (Facebook and Instagram) — that lets you reach new people who share similar characteristics to your existing customers or website visitors. The idea is straightforward: if you know what your best customers look like, you can ask the platform to find more people like them.

Lookalike audiences are one of the most powerful tools available in paid social advertising because they remove much of the guesswork from audience targeting. Instead of manually selecting interests and demographics, you let the platform’s algorithm identify patterns in your best customers and find new people who match those patterns.

How Lookalike Audiences Are Built

To create a lookalike audience, you first need a ‘source audience’ — a custom audience that the platform uses as a reference point. This could be a list of your existing customers (uploaded as a CSV of email addresses or phone numbers), people who have visited your website (tracked via the Meta Pixel), or people who have engaged with your content on the platform.

The platform analyses the characteristics of people in your source audience — demographics, interests, behaviours, and patterns it can observe within its own ecosystem — and then identifies a new audience of people who share those traits. On Meta, you can choose a ‘similarity percentage’ from 1% to 10% of a country’s population, with 1% being the most similar to your source and 10% being the broadest match.

A 1% lookalike is typically the strongest starting point: fewer people, but a closer match to your existing customers. As you scale campaigns and need to reach more people, widening to 2-5% increases the audience size at the cost of some precision.

Getting the Best Results from Lookalike Audiences

The quality of your lookalike audience depends entirely on the quality of your source audience. A source audience of 100 random website visitors will produce a weaker lookalike than one built from 1,000 confirmed purchasers. Wherever possible, seed your lookalike with your best customers — people who have bought more than once, spent above a certain threshold, or taken a meaningful action.

Lookalike audiences work best when combined with a clear creative strategy. Even the most precisely targeted audience won’t convert if the ad itself doesn’t communicate value clearly. Test different creatives against the same lookalike audience to find what resonates, then scale the winners.

Lookalike Audiences on Other Platforms

Meta is the most widely used platform for lookalike audiences, but similar features exist elsewhere. Google Ads calls its equivalent ‘Similar Segments’. LinkedIn offers ‘Matched Audiences’ with lookalike expansion. TikTok has its own ‘Lookalike Audience’ feature that draws on engagement behaviour within the platform.

Each platform’s lookalike feature is only as good as the underlying data it has on its users. Meta’s is particularly powerful because of the depth of behavioural and interest data across Facebook and Instagram. For B2B campaigns, LinkedIn’s version is valuable because it can identify professionals who share job titles, seniority levels, or industries with your existing clients.