MetricKPI Compass StandardApprovedInternal
Impression Share
The percentage of estimated eligible impressions that an ad or campaign actually received.
Definition
Impression Share compares delivered impressions with the estimated number of impressions the ad was eligible to receive under the platform's auction, targeting, approval, quality, and inventory rules.
Formula
Delivered impressions / estimated eligible impressions
Platform variations
How platforms implement this metric — external definitions, not competing internal ones. They often count differently, so review before combining.
Sources
- Google Ads HelpVerified 2026-08-04