Glossary/Brand & Performance Marketing/Impression Share
Brand & Performance Marketing
Impression Share
The percentage of eligible ad impressions you actually received, revealing how much demand you lose to budget or rank.
By Brandon Mina·CEO, BrandPilot AI·Updated November 2026
Short answer
Impression share is the percentage of eligible ad impressions an advertiser actually received, out of all the impressions it could have won. In search advertising, platforms report how much share was lost to budget limits or low ad rank. This reveals unmet demand and whether more budget or better quality would grow reach.