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A lookalike audience turns targeting around. Rather than picking interests, ages and regions yourself, you hand over a list of people who already became customers, and the platform searches its users for profiles that behave the same way. The better the list, the better the audience.
Meta launched lookalikes in 2013 and they became the engine of Facebook and Instagram advertising. Google called its version similar audiences until it retired them on 1 August 2023 under privacy pressure; since 2024 it offers lookalike segments again, mainly in Demand Gen campaigns on YouTube, Gmail and Discover.
Meta and Google side by side
| Meta | Google Demand Gen | |
|---|---|---|
| Seed | Customer list, pixel events, followers, video viewers | Customer list or your own data segments |
| Minimum seed | 100 people from one country | A data segment with enough active users |
| Sizes | 1 to 10 percent of a country's population | Narrow 2.5, balanced 5 or broad 10 percent |
| Where it runs | Feeds, stories, reels, Messenger | YouTube, Gmail, Discover |
In a market of 12 million people, a 1 percent lookalike is about 120,000 people. For a business serving one city that is already broad: combine the lookalike with a region, or treat it as a signal and let the platform search.
Three hundred customers as the seed, three rings around them
- 300customers in your seed list
- lookalike 1%120,000 peopleclosest to your seed
- lookalike 5%600,000 people
- lookalike 10%1.2M peoplemore reach, less similarity
Worked example for a market of 12 million people. Meta uses the population of the countries you choose.
Why consent decides the quality of your seed
A lookalike is only as good as its seed, and in Europe seeds have shrunk. Visitors must consent to Meta's cookie before your pixel can pass anything on, and those who decline drop out of your source data. A site that asks for consent clumsily or in a frightening way loses much of its signal. On the site we built for Park & Wash, a car detailing business, the consent request reads as a plain, friendly question, and the pixel fires only after a yes, with an event for every contact and enquiry. The seed is small but clean. What you must show is covered in do I need a cookie banner.
Customer lists carry their own rules: you upload them hashed, but the GDPR still applies, so only use data you are allowed to use for this and say so in your privacy notice.
What it does to your costs
A lookalike rarely lowers the price per thousand impressions, the CPM; it is often slightly higher, because other advertisers want the same people. What falls is the cost per result, the CPA, because the ad reaches people more likely to click and buy.
| Audience, same ad | CPM | CTR | Cost per lead |
|---|---|---|---|
| Everyone aged 25 to 65 in the region | €6 | 0.8% | €47 |
| Interests in renovation and interiors | €8 | 1.0% | €50 |
| 1% lookalike of 400 past customers | €9 | 1.5% | €38 |
A worked example in which 1.6 percent of visitors enquire in every row, so cost per lead is the cost per click divided by 0.016. Note the middle row: narrow interests make impressions dearer without enough extra clicks. Since Meta's Advantage+ may widen the audience on its own, a lookalike now often serves as a starting signal rather than a hard boundary. What Meta ads cost per objective is in Facebook ads cost, and how to choose between platforms in Meta ads or Google Ads.
Building a lookalike that works
- Seed it with buyers or enquiries from the past year, not all your followers: 300 real customers beat 5,000 likes.
- Upload customer lists hashed, and only data you may use for advertising.
- Start at 1 percent, the ring closest to your seed, then test 1 to 3 percent against it on cost per lead.
- Refresh the seed every quarter, or you keep finding people who resemble last year's offer.
- Send the clicks to a dedicated landing page, so the better audience is not wasted on a homepage.
What advertisers ask about lookalikes
How large should my seed be?
Meta needs at least 100 people from one country. In practice a few hundred to a few thousand real customers or enquiries work best.
Is a lookalike better than interest targeting?
Usually, when the seed is strong, because behaviour says more than interests. With a small or old seed, broad targeting sometimes wins.
Can I use a lookalike in several countries?
Yes. Meta builds it per country from your seed; a seed of customers in one market can find lookalikes in another, though they resemble each other less.