Fantôm’s In-Depth Guide To Facebook Lookalike Audiences

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Fantom's In-Depth Guide To Facebook Lookalike Audiences


In short, Facebook Lookalike audiences are a proven formula to help you reach audiences that are most like those that have already been to your website, engaged with your content, purchased from your site, called your business, and much, much more. It is an extremely powerful way to reach new prospects who are similar to your existing customers.


In 2013, Facebook first launched Lookalike audiences to allow advertisers to target prospects who are similar to their existing customers. The wealth of data that Facebook collects on it’s users has always been what sets it apart from other ad networks and what makes it a special place for marketers to reach new customers.

Facebook collects user activity data on Facebook and Instagram (who their friends are, what pages they like, posts they engage with, etc), but it also collects data on what it’s users do across the Internet. Any website that has a Facebook pixel, a like button or a “Sign up with Facebook” login system, is also sending data to Facebook regarding actions users perform while on that site or app; giving Facebook an overwhelming amount of data on each of it’s 2 billion users.

This is what allows Facebook to implement something like Lookalike audiences so successfully. When you create a Lookalike audience, you first upload a “source audience”, this can be an email list of every customer whoever completed a registration form, people who have shopped at your store before, people who have called your store, and more. Facebook crunches all the data it has stored about these users to find similarities among this group. The similarities are not just restricted to things like age or interests. A lot of what Facebook looks at are behavioral components too.

Facebook’s algorithm will start to query its entire user base looking for people who most closely share the profile and behavioral traits that it has detected from your source audience. The result is a Lookalike audience of prospects that are very similar to your source list.


In your Facebook Ads Manager, under the Audience section, there is a button called “Create Audience” which allows you to create a Custom, Lookalike or Saved audience.

Once you select Lookalike Audience, you will see a screen like the one below which requires a Source, Location and Audience Size in order to create the audience.


Source is the existing audience that you want Facebook to use as a base in order to create a Lookalike audience of people with similarities to those you have selected.

You can use an email list, a custom audience from your Facebook Pixel, or even just fans of your Facebook page.


The recommended source audience size should be at least 1,000 people or more, the bigger the audience, the better. Facebook’s algorithm is going to try to find a strong Lookalike match. For best results, the quality of your source audience really matters, too.

A source audience made up of your most loyal repeat-purchase customers will be much better than a source audience of people who just bought from you once, for example.

What if you don’t have 1,000 past purchasers/visitors/etc?

If you don’t have a list size of 1,000 people who have previously engaged with your brand in some way, here are a few other sources you can use instead:

  • Only have 100–200 past purchasers? Just use them anyway and forget about the 1,000 minimum! (your Lookalike audience just won’t be as strong)
  • Have an email subscriber list? Use that as the source audience (ideally use the most engaged subscribers e.g. the ones who open/click your emails).
  • Have some website visitors? Create a custom audience of people who visited your website, ideally the pages you want people to be looking at.
  • Have some fans on Facebook? Use your Facebook fans as your source audience to create a lookalike.
  • Have people engaged with your content on Facebook? Use people who engaged with your brand to create a lookalike audience.
  • Put out a lot of video content? Create a lookalike of people who have watched three, or ten seconds of your videos.


The audience percentage selection simply means how big of an audience size do you want Facebook to find, as a percentage of the total population you’ve selected. For example, if you choose the United States and 10%, you’ll get back an audience size of roughly 21M people.

To start off, you should be creating most of your audiences with 1% audience size, these will be the people that most closely match those you’ve submitted in your source lists to create the Lookalike audience.

We usually start at 1% and once we feel like we’ve scaled as far as we could with that audience, we start to broaden out to 2%, 3%, etc. But it will take 10s of thousands of dollars in ad spend (or more) before that starts to happen, so no rush.


Becoming overwhelmed can be extremely easy with all of the different types of audiences, ads, experiments, etc. When you’re just getting started, the best approach is to start off simple and add more complexity as you go.

Driving high-quality traffic to your site is essential, but once you start driving traffic, you’ll want to have a solid retargeting strategy in place as well. On average, 98% of visitors will leave without completing a purchase. Retargeting allows you to get in front of those users again and encourage them to come back.


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