Impressions vs reach
Impressions count ad deliveries; reach counts distinct people. One person who sees an ad five times is five impressions and one reach, and the ratio between them is frequency. Impressions are counted by every ad server; reach requires recognizing the same person across deliveries, which platforms can do within their own systems and only estimate across them.
| Impressions | reach | |
|---|---|---|
| Counts | Deliveries | People |
| Duplicates | Included | Removed |
| Measured by | Ad server, exact | Platform identity or panel, estimated |
| Priced by | CPM | Cost per thousand reached, CPP |
| Relationship | Impressions = reach x frequency |
Terms in this comparison
Cite this page:
Agency Echelon. "Impressions vs reach." Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/compare/impressions-vs-reach/