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# Viewability
- URL: https://www.adlingo.org/glossary/viewability/
- Published: 2025-01-15T09:06:00.000Z
- Updated: 2025-01-15T09:06:00.000Z
- Description: A metric that tracks whether an ad impression was actually viewable by a human user, typically requiring 50% of display ad pixels to be in view for at least one continuous second.
- Author: Travis Lusk
- Tags: Measurement, #glossary, #Import 2026-10-27 17:05

The MRC standard defines a display ad as viewable when 50% of pixels are in view for at least one continuous second. Video requires 50% of pixels in view for two continuous seconds. Those thresholds are floors, not performance targets. An ad that barely clears the viewability standard is not an ad anyone engaged with. The real question is what viewability rate you're actually achieving, how it compares to benchmarks for the placement type, and what your verification vendor classifies as unmeasured versus non-viewable.