Viewability
A metric measuring whether an ad was actually visible to a user, based on industry standards for pixels-in-view and display duration.
What Viewability means
Viewability measures whether an ad had the opportunity to be seen by a user, based on the Media Rating Council (MRC) standards: display ads must have at least 50% of pixels in the viewable area for at least 1 continuous second, and video ads must have 50% of pixels visible for at least 2 continuous seconds. Viewability is critical for ensuring ad spend delivers actual value — non-viewable impressions waste budget and distort performance metrics. Third-party viewability vendors (IAS, DoubleVerify, MOAT) provide independent measurement and verification. Platforms report viewability metrics with varying levels of detail. From a compliance perspective, selling non-viewable inventory as premium placement, inflating viewability metrics, or failing to disclose viewability issues may constitute fraudulent practices. The industry trend is toward 100% viewability standards, though this remains aspirational.
Related terms
Impressions
The number of times an ad is displayed on a screen, regardless of whether it was actually seen or clicked.
Cost Per Mille
The cost per thousand impressions, a standard pricing model for display and video advertising.
Brand Safety
Measures taken to ensure ads do not appear alongside harmful, offensive, or inappropriate content that could damage brand reputation.
Ad Fraud
Fraudulent activity that manipulates ad delivery, clicks, or conversions to generate illegitimate revenue or inflate metrics.