Google Ads gives Demand Gen advertisers a way to keep Lookalike targeting restrictions

Google Ads is preparing to change how Lookalike audience segments work in Demand Gen campaigns, moving their default behavior toward audience suggestions rather than strict targeting restrictions.

Why it matters. Lookalike segments have traditionally helped advertisers reach new people who share characteristics with their existing customers. Moving toward suggestion-based targeting could give Google’s AI more flexibility to find conversions, but it also means advertisers may have less control over who sees their ads.

What’s changing. Google says Lookalike segments will evolve toward a suggestion mode by default. Advertisers who want to preserve the original behavior can opt out and continue using Lookalike segments as a targeting constraint.

The key difference. With targeting constraints, advertisers can restrict delivery to their selected Lookalike audience. Suggestion-based targeting gives Google’s systems more flexibility to use that audience as a starting point rather than a strict boundary.

How it works. Lookalike segments use first-party data, including customer lists, website visitors, app users and YouTube audiences, to identify potential customers with similar characteristics.

The targeting options: Advertisers can choose between three Lookalike audience sizes:

• Narrow: Targets the most similar 2.5% of users in the selected location.
• Balanced: Expands the audience to 5%.
• Broad: Reaches up to 10%, trading some similarity for additional scale.

The requirements. Lookalike segments need more than 100 active matched users across their seed lists. Google refreshes these audiences every one to two days, helping keep targeting aligned with recent customer activity.

Why we care. The change could significantly affect how Demand Gen campaigns reach potential customers. Advertisers relying on tightly defined Lookalike audiences may want to preserve targeting constraints, while those prioritizing reach and conversion volume may prefer Google’s more flexible approach.

Yes, but. Expanding beyond a Lookalike audience doesn’t automatically mean better performance. Advertisers should monitor conversion quality, acquisition costs and customer value to determine whether broader targeting delivers genuinely useful growth.

The bottom line. Demand Gen advertisers will have a choice between maintaining strict Lookalike targeting and allowing Google’s AI more flexibility. Those who want to preserve the existing behavior should review Google’s opt-out option before the default changes.

Dig deeper. Google Ads — Use Lookalike segments in Demand Gen campaigns as a Targeting Constraint