Viewability
Viewability is the percentage of impressions that meet IAB standards for being seen: at least 50% of pixels in view for at least 1 second (display) or 2 seconds (video).
Viewable Rate = (Viewable Impressions / Total Impressions) × 100What does Viewability actually mean?
Viewability measures whether served impressions were visible to users. The IAB standard: 50% of pixels in view for at least 1 continuous second for display ads, or 2 continuous seconds for video. Impressions that don't meet this threshold are considered ‘non-viewable’ even though the platform served them.
Viewability has historically been a major issue in programmatic display where ads serve below-the-fold or in fraudulent placements. Industry-average display viewability runs 60-75% across major exchanges. YouTube and CTV report higher numbers (85%+) because format and placement favor visibility.
Measurement is dominated by IAS (Integral Ad Science), DoubleVerify and Moat (Oracle). Most premium DSPs include viewability data in reporting. For brands buying programmatic at scale, viewable-CPM (vCPM) is the more honest cost metric than raw CPM.
Example
A programmatic display campaign serves 1M impressions; 720K meet IAB viewability standards. Viewable rate = 72%. The 280K non-viewable impressions effectively wasted spend, even though they were charged.
When it matters
Viewability is critical for programmatic display and CTV. For Meta and TikTok native ads it's less of a concern (placement is in-feed). Brand-safety and viewability often track together.
Related terms
Brand safety
Brand safety is the discipline of preventing ads from appearing alongside harmful, controversial or off-brand content.
CPM
CPM is the cost to serve 1,000 impressions of your ad. It signals audience competitiveness and seasonal demand.
Programmatic advertising
Programmatic advertising is the automated buying of ad inventory through real-time auctions, replacing direct media buys with software.
CTV
Connected TV is internet-delivered television (Roku, Apple TV, smart TVs, Hulu, Netflix Ads), increasingly bought programmatically.
Find out which ads actually win.
advrt builds ads around your real product photos, tests them live on Meta and judges each one against your own account. Free plan, no credit card.