Audience Measurement
Viewability
A digital and advanced television metric determining if an ad was actually rendered on a screen long enough to be perceptually seen by a human.
What is Viewability?
Viewability measures whether an impression was even capable of being seen. The IAB's base standard requires that at least 50 percent of a display ad's pixels be visible for at least one continuous second; video ads require 50 percent visibility for at least two continuous seconds. Below those thresholds, an impression is technically served but not viewable — and increasingly, not paid for under modern media contracts.
For CTV, OTT, and streaming audio, viewability and audibility are the analogues to 'reach' in linear broadcast. Advertisers refuse to pay for served-but-unseen impressions; publishers must therefore instrument their players to measure viewability and, increasingly, to refund non-viewable delivery. This has become one of the largest disputes between advertisers and streaming platforms.
Why it matters
A crucial top-of-funnel metric; an impression holds zero value to an advertiser if the ad was mathematically delivered but not viewable.
Related terms
- Arbitron / Nielsen Audio— The legacy and current primary authoritative bodies for radio audience measurement in the United States.
- Reach— The absolute number of distinct, individual audience members exposed to a specific advertisement or campaign at least once.
- Actives vs. Passives— Active listeners actively contact radio stations for requests or contests; passive listeners consume the media without direct engagement.
- Aided Recall— A research methodology used to test audience memory retention of advertisements by providing specific prompts or hints to the respondent.