// glossary
Audience Overlap.
Definition + measurement
Audience overlap happens when the same user is targeted under multiple audiences (remarketing, similar audiences, customer match, in-market) and ends up seeing your ad through multiple lists at once. Typically eats 4-10% of spend silently and breaks frequency capping.
// detail
Typical problem: marketing teams build different audiences for different goals — remarketing for cart abandoners, similar audiences for lookalikes, in-market for purchase signal. These often overlap 20-40%; the same user becomes a candidate in each.
Detection: Google Ads → Tools → Audience Insights → Audience Overlap report. Shows overlap percentage between every pair. Pairs with 20%+ overlap warrant attention.
Example: A "cart abandoners last 30 days" remarketing audience overlaps significantly with a "site visitors last 90 days" remarketing audience — likely 50%+. Fix: subtract the narrower audience from the broader one (negative audience).