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Ad Viewability

What is ad viewability?

Ad viewability is a key metric in digital advertising that tracks the ads which have been viewed by real human beings rather than by bots.

At its substance, ad viewability looks at the number of ads served by digital advertisers actually getting seen by users. The generally agreed-upon industry standards for ad viewability come from the Interactive Advertising Bureau (IAB) and Media Rating Council (MRC), whereby an ad impression is considered viewable if:

  • For desktop display ads, 50% of the ad’s pixels are visible for at least 1 second
  • For desktop video ads, 50% of the ad pixels are visible for at least 2 seconds
  • For large desktop units, 30% of pixels are visible for at least 1 second

The MRC has also proposed similar viewability standards for mobile devices.

How to measure ad viewability?

Viewability rate is the percentage of total ad impressions that were estimated as viewable. The formula to calculate the viewability rate is as below:

Viewability Rate Formula
Image source: MobileAds

Therefore, if your average ad viewability is below 50%, it is likely that your ad is not being viewed or is being skipped by the target audience. The reasons for the same are discussed in the below section.

Why ads may not be viewable

A few of the most common reasons for ads not being viewable are summed up below:

  1. The ad is not positioned above the fold: This refers to the topmost part of any web page which is visible without scrolling. If the ad is not placed here, it can be missed either due to poor placement or due to small screen size (smartphones).
  2. The user is using an ad blocker: The user may be using an ad-blocking service that either hides the ads or prohibit them from loading at all. 
  3. Invalid traffic: This refers to any kind of non-human traffic mainly consisting of bots that are programmed to spike impressions and CTRs leading to falsified traffic/ad fraud.
  4. The user has multiple tabs open: This is a very common multitasking practice among desktop users. Users click on another tab to browse through a different page while the ad plays through simply because they don’t want to watch it and have no option to skip it.

Importance of ad viewability

56% of digital ads served are never seen by users


This means that more than half of the ads served are not getting viewed by users, causing advertisers to waste millions of dollars in ad spending each year. And for a publisher, this means a decrease in the value of their ad inventory.

Due to the factors mentioned earlier, all ads served are not necessarily being viewed. As a result,  the advertising industry is presently moving into valuing viewable impressions rather than served impressions, which we now know, can be falsified. Nowadays, advertisers tend to bid for viewable impressions as they have a better chance of their ads being seen by users.

Below are a few reasons why viewability is vital for digital advertisers:

  • It ensures tracking real human views vs tracking bots.
  • It allows tracking which ads encourage more viewership and engagement.
  • It gives insights that help to decide the ad placement, hence ads are more likely to be viewed.
  • It helps in reducing advertising costs as ad platforms charge based on viewable impressions. 
  • It also helps in comparing the effectiveness of ads served on digital media as compared to other media like TV & print.

Importance for publishers:

Viewability is important for a publisher also, as:

  • It helps them in understanding the real performance and effectiveness of each ad placement space.
  • It helps them to re-evaluate and adapt to viewability technology to satisfy the advertiser’s demands.

How to improve ad viewability?

Let’s learn about little tricks that will help publishers to increase their served impressions while attracting high-paying ad campaigns to their sites:

  1. Ad size
    1. It is to be believed that ads that are shorter, relevant, and crisp with engaging content, attract better user viewability as compared to others. 
    2. Ad viewability on vertical ads is higher than others, as these ads span the entire page as the user scrolls.
    3. Implementing sticky ads can be a good idea as they stay visible within the browser viewport resulting in higher viewability.
  1. Ad position/layout –  The position of an ad is strongly correlated with its viewability. Ads can often be placed either above or below the fold. Many types of research conducted have found that above-the-fold ads have more viewability as compared to ads placed below the fold. However, it doesn’t mean that they are not worth considering. As a solution to this, A/B testing can be performed to see what works best.
  2. Page load speed – Users tend to leave pages that take too long to load. An excellent page loading time is the key to a great user experience. Many technical adjustments like, enabling file compression, reducing redirects, and optimizing images can be done to ensure high load speeds for pages. 
  3. Lazy load ads – Lazy loading is a process to delay loading parts of the page that are out of view until the user scrolls down. It is recommended to lazy load below-the-fold ads which have a poor ad viewable impressions rate and are missed out most of the time. This improves site speed along with viewability.
  4. Responsive ads – A well-designed responsive ad ensures a good user experience. It makes sure that the ads adapt depending on the browser and platform used for viewing.
  5. Optimize mobile devices – A high level of optimization for mobile devices can do wonders for viewability.
  6. Reduce bounce rate – Bounce rate is the measure of the percentage of users exiting a website without doing any meaningful interaction. This means the user doesn’t get the chance to see an ad which can lead to low viewability. Resolving the underlying problems such as website design, page speed, content quality, etc. can improve bounce rate hence the viewability.  Read more to learn how to reduce bounce rate.
  1. Using better ad channels – Trying and analyzing data from ad channels based on the target audience, purpose, the volume of traffic, etc. can help select the one which works best for the marketer.