What is Ad Viewability? Understanding the Concept of Ad Visibility

Ad viewability is a crucial aspect of digital advertising that determines how visible ads are to users on websites or mobile apps. According to the Internet Advertising Bureau (IAB), for an ad to be considered “viewed,” at least 50% of the banner or creative must be displayed on the screen for more than one second. This standard defines what constitutes a viewable impression, providing a basis for measuring ad visibility and performance.

Why Ad Viewability Matters in Digital Advertising

Ad viewability has emerged as a significant concern in digital advertising, especially since a comScore report revealed that 54% of display ads were not being seen by users, despite advertisers paying for them. In the early days of internet advertising, ad networks focused more on the number of ads served rather than the number of ads viewed. Metrics like clickthrough ratio (CTR), which calculated the relative success of a campaign based on clicks divided by ads served, were commonly used.

As online advertising matured, advertisers began questioning the validity of using ads served as a proxy for ads viewed. They realized that certain factors could impact ad visibility, such as ads being placed below the fold where users may not scroll down to see them, or instances where users clicked away before the ad loaded. Additionally, the presence of bots and proxy servers opening pages further hindered ad visibility.

Because of these issues, advertisers now demand that publishers measure and report the percentage of their ads that are genuinely viewable, and they structure their advertising rates accordingly. Ensuring ad viewability is crucial for media companies to keep their advertisers satisfied and maintain their revenue streams.

Illustration of visible ads on a website. d Viewability

Improving Ad Viewability: Strategies for Publishers

As improved ad viewability correlates with higher returns on investment, publishers should prioritize enhancing the visibility of their ads. Here are some effective strategies they can implement:

1. Designing for Viewability

Publishers can design their web pages in a way that maximizes ad viewability potential. This may involve placing ad units “above the fold,” ensuring they are visible as soon as users land on the page. Additionally, employing “sticky” ad units that remain fixed in a specific location as users scroll can also boost viewability.

2. Mobile-Friendly Websites

With a significant portion of web traffic coming from mobile devices, publishers must adopt responsive templates that adjust the page layout based on the device being used. This ensures a positive user experience, regardless of whether users are accessing the content on a tablet, phone, or desktop.

3. Prioritizing Design Principles

Following good design principles, such as creating a clear visual hierarchy, maintaining symmetry, using pleasing proportions, incorporating ample white space, and employing clean design, can enhance ad viewability.

4. Speed Optimization

Websites laden with ads from multiple ad networks may experience slower loading times. Publishers should focus on techniques to speed up ad delivery, reducing the risk of users clicking away before the ads have a chance to load.

5. Measuring and Validating Viewability

Publishers can leverage third-party software to measure and validate ad viewability. Sharing these metrics with advertisers showcases transparency and helps build trust.

Utilizing A/B Testing for Improved Viewability

Viewability data offers publishers a way to enhance the value of their display inventory. By seeking out publishers with higher viewability rates, advertisers and digital marketing teams can maximize their advertising impact. Sharing viewability data makes it easier for brands to compare rates across multiple publishers and make informed decisions about their ad placements.

Publishers using Optimizely can integrate with Moat, a leading viewability analytics platform, to set up A/B tests. These tests allow publishers to experiment with different page layouts, optimizing ad placement and performance. Ultimately, this process leads to higher ROI for digital ad campaigns and ensures that an ad served results in an ad impression.


Ad viewability is a critical aspect of digital advertising that directly impacts the effectiveness of ad campaigns. Publishers must prioritize improving ad visibility to maintain advertiser satisfaction and boost revenue. Through strategic design, mobile optimization, speed improvements, and A/B testing, publishers can elevate their ad viewability and deliver better results for advertisers.


What is ad viewability, and why is it important?

Ad viewability refers to how visible ads are to users on websites or mobile apps. It is essential because it ensures that advertisers get their money’s worth, as ads are viewed by their target audience.

How can publishers improve ad viewability?

Publishers can enhance ad viewability by designing pages for maximum visibility, using mobile-friendly templates, prioritizing design principles, optimizing website speed, and leveraging A/B testing.

Why did advertisers shift focus from the number of ads served to viewability metrics?

Advertisers realized that merely serving ads does not guarantee they will be seen by users. Viewability metrics offer a more accurate measure of ad effectiveness.

How can publishers validate ad viewability?

Publishers can use third-party software and partner with Media Rating Council (MRC) Accredited Viewable Display Impression and/or Ad Verification Vendors to validate ad viewability.

What benefits does A/B testing offer for ad viewability?

A/B testing helps publishers identify the most effective ad placements and layouts, leading to higher viewability rates and improved ROI for ad campaigns.

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