Lookalike Seeds

Select, size, and validate the seed customer list that a lookalike, similar, or value-based audience will be built from. Three principles govern every step below:

• Match count, not row count - every uploaded list shrinks by its match rate before it reaches the platform's minimum. A 40% match on 5,000 rows is a 2,000-person seed, and the platform floor applies to that matched number - upload 2-3x the target.
• Homogeneity and value concentration beat size - Meta's own guidance holds that a seed's homogeneity affects audience effectiveness more than its size. Practitioner consensus (Stackmatix, Grow With Sakib - directional, not audited) is that a few hundred high-value customers outperform thousands of undifferentiated subscribers.
• Inclusion is a suggestion, exclusion is a rule - on Meta (Advantage+) and Google (Demand Gen, where lookalike reach tiers now function as signals rather than hard segments), the delivery algorithm may override an inclusion audience. Only exclusion/suppression audiences remain hard rules.

The seed's job is feeding the algorithm the cleanest signal, not fencing an audience - which raises the quality bar rather than removing it.

This skill ends at a specified, validated seed definition plus its export/handoff spec. It never walks through creating or uploading the audience inside any ad platform's interface.

Where each adjacent concern lives: