Lookalike segments
Lookalike segments are audiences of people who share characteristics with a store's existing customers or visitors, built from a seed list the store provides.
How it works
You give Google a seed, the people to start from. It can be up to 10 lists built from your first-party data, such as customer lists, website visitors or YouTube viewers. Google then looks for similar people in the countries or regions you choose.
In Google Ads you create lookalike segments in Demand Gen campaigns; Google’s documentation says other campaign types show them as “Eligible - Limited”. Whether a store is ready for Demand Gen: Demand Gen campaigns for online stores.
A slider sets the reach: Narrow, Balanced or Broad, aimed at 2.5%, 5% and 10% of users in the target location. During 2026 Google is moving lookalike segments in Demand Gen to a suggestion mode. In it, the seed and the slider become signals, and the campaign may reach people beyond those limits. Advertisers who want the old limits can opt out.
Meta’s Lookalike Audiences also start from a seed audience in a chosen country. Google built its older similar audiences itself and removed them from campaigns in August 2023.
Where you see it
Google Ads: in a Demand Gen ad group, the audience section has “Add or create Lookalike segment” with the slider. In reports, a “signal” tag next to a lookalike segment means suggestion mode is on.
Not to be confused with
- Audience signals — hints in a Performance Max asset group. You choose a lookalike segment in a Demand Gen ad group, and it does not work in Performance Max.
- Customer Match — your own customers, uploaded as a list. It can serve as the seed; the lookalike segment is the new people Google finds from it.
Right and wrong readings
- Wrong: “Balanced means the ads reach at most 5% of the country.” Right: in suggestion mode the slider is a signal. The 5% limit holds only where suggestion mode is off.
Sources
- Use Lookalike segments to grow your audience — suggestion mode, opt-out, “signal” tag. Checked 2 October 2026 (archived copy of 13 September 2026).
- Use Lookalike segments in Demand Gen campaigns as a Targeting Constraint — seed lists, reach options. Checked 2 October 2026 (archived copy of 16 April 2026).
- Lookalike audience segments — Demand Gen only, “Eligible - Limited”. Checked 2 October 2026.
- Changes to audience targeting: Google Ads will no longer support similar audiences (also known as “similar segments”) — removal in August 2023. Checked 2 October 2026 (archived copy of 17 September 2024).
- SimilarUserListInfo — similar lists were built by Google. Checked 2 October 2026.
- Lookalike Audiences — Meta: seed, country. Checked 2 October 2026.