Lookalike Audience Expansion is a Meta feature that automatically broadens a defined lookalike audience beyond its original percentage boundary when the algorithm identifies high-value users just outside that range. Unlike a standard 1–2% lookalike which strictly targets the most similar users, expansion allows Meta to reach slightly less similar users if it predicts they are likely to convert. This feature is part of Meta’s broader move toward automation and audience loosening introduced in 2024–25. Advertisers should monitor it closely, expansion increases reach but can sometimes dilute targeting precision for niche offers.