Viewability measures whether an ad had a chance to be seen — typically 50% of pixels in view for at least one second (display) or two seconds (video), per MRC/IAB standards. Served impressions exceed viewable impressions on long-tail Display and Audience Network; compare CPM on viewable basis when auditing partner inventory.
Platforms report “viewable impressions” differently — export raw logs for audits, not just dashboard totals.
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Last verified Jun 4, 2026