What is Viewability?
Viewability is the percentage of impressions that met a visibility threshold (e.g., 50% of pixels in view for 1 second for display, 2 seconds for video).
Understanding Viewability
Viewability tracks whether ads met technical visibility standards set by organizations like the MRC (Media Rating Council). For display, this typically means at least 50% of pixels were in view for at least one continuous second. For video, the threshold extends to two seconds. These standards help ensure advertisers pay for opportunities to be seen, not for impressions that load below the fold or in hidden tabs where users never encounter them.
Viewability is a prerequisite for attention and performance, but high viewability alone doesn't guarantee results. Pair viewability tracking with downstream metrics like CTR and conversion rate to understand true impact. Native aspect ratios and standard ad sizes tend to achieve higher viewability because platforms prioritize them in more visible placements. Monitor viewability by site, app, and placement to identify and exclude chronic underperformers that drain budget without delivering exposure.
Why Viewability matters
Viewability matters because paying for unseen impressions wastes budget and distorts performance data. When viewability is low, you're funding inventory that never had a fair chance to drive outcomes. Improving viewability also creates a cleaner foundation for creative testing and optimization.
- Waste reduction: Avoid paying for unseen impressions.
- Optimization: Improve placements and creative sizes.
- Measurement: Clearer attribution when ads actually load in view.
How Viewability works
Viewability works through measurement tags that track when ad pixels enter the user's viewport and for how long. Platforms and third-party vendors report the percentage of impressions that met the defined threshold, allowing you to compare placements and publishers. Native aspect ratios and standard sizes tend to score higher because they fit feed and page layouts without requiring excessive scrolling. Above-the-fold placements naturally achieve better viewability, while below-the-fold spots vary by page length and user behavior. Monitor viewability by site and app, then exclude or renegotiate with sources that consistently underdeliver. Combine viewability data with performance metrics to avoid optimizing for visibility at the expense of actual conversions.
