What Is Viewability & Why Is It Important For Advertising Campaigns

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  • Post last modified:April 23, 2020

You might have heard about viewability in the digital advertising sphere.

However, due to the speed of technology advancement in digital advertising, there is still confusion about what viewability is, what the standards are and why it matters for digital advertisers.

In this post, we will explain what viewability is, why is it important, how it works and most importantly, what causes ads to be not ‘viewable’.

Now, let’s start.

What Is Viewability?

Viewability is a metric in digital advertising that tracks ad impressions which are actually seen by real humans. These impressions are called ‘viewed impression’, not to be confused with impressions on a computer or mobile screen. In simple words, if you have an advertisement that shows at the bottom of a website and a visitor does not scroll far enough to see it, a viewed impression will not be recorded.

Back in 2011, the IAB, ANA (Association of National Advertisers & 4A’s (American Association of Advertising Agencies) joined forces in an attempt to fix digital measurement, a known challenge to advertisers.

This brought about the viewable impression metric to measure accountability of the platforms. Ads are served by shifting from measuring served impressions to measuring viewable impressions.

Also with viewability, advertisers can now more effectively compare the effectiveness of their ads served on digital media as compared to other media like TV & print.

Additional Resources:
How to Measure Viewability Using MobileAds’ Audit Tool
How to Identify Bad Inventories in Display Ad Campaigns

What causes ads to be not ‘viewable’?

Many online display ads end up being shown in ad placements where real users never see them. There are a few reasons why this happens. Commonly, because the ad might be hidden behind another browser or tab.

Let us go through the few scenarios that causes ads to be not ‘viewable.’

Ad is not ‘above the fold’ of a web page


This has to do with the design of the web page and placement of the ad. The term ‘above the fold’ refers to the top portion of the web page which is visible without a user having to scroll around.

Users are viewing web pages using different types of smartphones, tablets and desktop computers that come in all sorts of screen sizes.

When an ad loads below the fold, due to a certain screen size the user is on, the ad is not viewable.

When the user is using an ad blocker


Ad blockers are usually browser plugins or filters that work on a network level. They serve to hide ads or completely disable them from loading.

The problem is some ad blocking programs only scan a page after it’s loaded and looks for patterns or HTML that contains ‘ad’. It then either hide or removes them. To an ad network, the ad is served, and an impression is recorded, but it’s not visible on the screen.

With viewability implemented, you can measure whether the ad is visible in the browser and if a user sees it.

Non-human or bot traffic to websites

Another issue that causes an ad to not be viewable is due to non-human or bot traffic. Created by the automation of bots, they can falsify traffic and even click through rates. This is counted as an ad fraud, which we’ll talk about later.

User is on another tab or in another program while ad plays


When an ad is shown to a user on a page, they can click on another tab or browse into another program while the ad plays. This is a very typical scenario that happens on desktops causing ads to not be viewable.

Viewability also varies across different industries and content. According to Google, content that can hold the attention of users will often have the highest ad viewability.

Why is Viewability Important?

According to Google, 56% of ads are not seen by users.
According to Google, 56% of ads are not seen by users.

“56% of digital ads served are never seen by users” – Google

With more than half of served ads not getting viewed by users, this causes advertisers to waste millions of dollars in ad spend each year. And towards a publisher, this decreases the value of their ad inventory.

Ads that you serve are not necessarily being viewed, due to the factors we mentioned earlier.

Therefore, the advertising industry is currently moving into valuing viewable impressions rather than served impressions, which we now know, can be biased. Today, advertisers tend to bid for viewable impressions as they have an increased chance of their ads being seen by users.

According to the IAB, digital measurement is the single greatest obstacle to the growth of most advertising & marketing agencies. Many advertisers are still judging the effectiveness of their advertising campaigns by looking at metrics like click-through rates(CTR) and cost per thousand(CPM).

These metrics might be the industry standard metrics used to track ad effectiveness, but results can be inaccurate. Besides, there is also a lot of fraud in the digital advertising world, with bots acting like humans. This means when you pay for impressions as an advertiser, you’re not paying for a guarantee that real humans are viewing your ad.

There are a few reasons why viewability is important for digital advertisers.

  • Viewability ensures you track real human views VS bots
  • Viewability allows you to track which ads encourage more viewership & engagement
  • Viewability will give you insights to decide where to place ads that are more likely to be viewed.

Most importantly, viewability ensures that you are tracking real human views when running your advertising campaigns.

As an advertiser, you also reduce your advertising cost by working with ad platforms that charge based on viewable impressions.

Viewability is important towards a publisher as well as it helps them understand the real performance of each ad placement space. For the publisher, viewability means they must re-evaluate and adapt viewability technology to satisfy the demands of advertisers.

Additional Resources:
How to Measure Viewability Using MobileAds’ Audit Tool
How to Identify Bad Inventories in Display Ad Campaigns

What is ad fraud and how is viewability helping?

You’ve probably heard of ad fraud if you’re in the digital advertising industry. Billions of advertising budgets are lost to ad fraud and it’s a serious problem.

Here are some findings on ad fraud, per a report by the (ANA) Association of National Advertisers with WhiteOps, a digital security company.

  • Bot impressions have increased up to 37%, from the year before, where the highest percentage recorded was at 22%.
  • Sites with higher ad rates are targeted by fraudsters, as the ad buys are worth more money. Display ads with higher CPM (at least $10 per 1000 impressions) had 39% more bots than ads with lower CPM.
  • More bots are observed in programmatic ad buys. Programmatic display ads saw an increase of 14% in bot traffic and programmatic video experienced an increase of 73% more bots.

A fraudulent ad is an ad impression that a real human never see. Both real humans and/or bots can generate fraudulent ad impressions. Highly sophisticated, these bots can mimic a human to click on links, act as website traffic and can be targeted to with ads, just like a real human user.

Some publishers who want to increase the value of their ad inventories often turn to purchasing traffic from dodgy affiliate networks and third parties. Unfortunately, a lot of this bought traffic are generated from bots, regardless of whether the publisher intended for it or not.

Some ways to battle bots in your advertising campaigns are:

  1. Only measure performance metrics that matters. Viewable impressions are so much more valuable compared to only measuring impression served.
  2. Work with ad vendors who provide viewability. Sometimes publisher themselves are fraudsters, so always work with trusted ad vendors who provide viewability & transparency into their data measurement.
  3. Assess & review your ad campaigns. It is suggested that you actively review the traffic coming to your ads and understand who are clicking on your ads. That will give you the insights to adjust your ads when necessary.

Additional Resources:
How to Measure Viewability Using MobileAds’ Audit Tool
How to Identify Bad Inventories in Display Ad Campaigns

Ad Viewability Standards & How Digital Measurement Works?

The MRC (Media Rating Council) has set a viewability standard definition for advertisers & publishers to understand how the viewability metric works and how it is measured.

Under the lead of MRC, for ads to be considered viewable:

  • Desktop display ads must have 50% of the ad in view for at least 1 second
  • Desktop video ads must have 50% of pixels in view for at least 2 seconds.
  • Larger desktop ad units, with 242, 500 pixels and larger must have 30% of pixels in view for at least 1 second.

The MRC also proposed the same viewability standards for mobile ads where at least half the ad must be viewable for 1-second for display ads and 2-seconds for video ads.

However, because the viewability standards and metrics are still constantly evolving and under development, there is no consistent viewability standard for custom ad units, even though more and more advertisers & ad agencies are insisting that they only pay for ad campaigns that track viewable impressions.

There are also ad vendors & platforms like Facebook & LinkedIn that use their methods and technologies to determine whether an impression meets the viewability criteria or not.

As an advertiser, you should stay informed & educated on the viewability standards used by your ad vendors. Before you start paying for any advertising campaigns, make sure to choose an ad vendor that utilizes an ad measurement metric that matches your expectations.

How to Measure Viewability Rates & The Viewability Benchmarks

Now that you know the standard definition for ad viewability, we want to show you how to measure viewability rate. Viewability rate is usually expressed as a percentage.

Currently, ad vendors are not able to measure 100% of total ad impressions. ‘Measured ad impressions’ are used instead. ‘Measured ad impressions’ is the number of ad impressions that can be measured by an ad vendor.

viewability rate equation

The above is the formula to get viewability rate expressed in percentage. If you know how many viewable impressions and measured ad impressions you can get from your advertising campaign, you’ll be able to calculate your viewability rate. You can also try the viewability rate calculator and viewable impressions calculator by The Online Advertising Guide.

Ad management firm, Sizmek, who analyzes viewable data from over 240 billion impressions in 2014, reports that:

  • Ads that meet the threshold of 70% viewability or higher as recommended by the IAB performed better than ads below the viewability threshold.
  • Viewability increased as advertisers began to adopt more interactive ad formats
  • HTML5 improves viewability rates as compared to Flash
  • Mobile specific creatives have higher viewability than desktop sized creatives
  • Ads that are served directly to publishers have higher viewability than programmatic ads.
  • For both publisher direct and DSPs, mobile specific-sized ads were still more viewable compared to desktop.

Ads with 70% viewability or higher performed better in terms of click-through rates and interaction rates. This shows that the IAB is spot on when recommending the viewability standards of at least 50% of the ad being in view for at least 1 second.

Interactive and rich media ad formats are also reported to beat static banner ads in ad performance. Most importantly, regardless of how mobile ads were served, they reported higher viewability rates as compared to desktop ads. This confirms the shift of the advertising industry to investing in more rich media ads on mobile platforms.

Is it possible to achieve 100% viewability in ad campaigns?

The ANA, 4A’s & IAB are working hard with the aspiration to make all digital media viewable in all advertising campaigns. However, because of the technology limitations we have today, it’s not reasonable to achieve 100% viewability in ad campaigns.

Ad vendors who adopted the viewability metric are reporting most ad campaigns can have a varying viewability data between 30% to 40%.

It’s currently impossible for an ad vendor to measure 100% viewability accurately. There are too many inconsistencies happening in high impact placements like page takeovers, roadblocks and custom placements which are not consistently measurable.

However, the goal of the IAB is to achieve 100% viewability. The viewability metric will improve over time with the MRC continuing to improve and innovate the state of viewability.

Additional Resources:

Best Practices to Lift Your Ad Viewability Score
How to Measure Viewability

Key Features An Ad Viewability Vendor Should Have

By now, you should know that its crucial to have an ad viewability vendor, as part of your ad campaigns. Not all ad viewability vendors are the same though. Here are 3 key features to look for:

1. Detailed Ad Viewability Reporting

What Is Viewability & Why Is It Important For Advertising Campaigns 1

Is your ad viewability vendor able to track the viewability of your ads by a breakdown of the sites and placements they were served into? By knowing exactly which sites or apps are providing good viewability, you can optimize your ads effectively by blacklisting those providing low viewability and white-listing those providing high viewability.

2. Customizability

Most ad viewability vendors follow ad viewability standards set by the MRC. However, you may come across certain campaigns, where you are required to measure more specialized metrics beyond viewability, such as dwell time on the ad.

How customizable is your current ad viewability vendor? Are you able to tweak reporting metrics or request for custom tracking reports? Because every campaign tracks success metrics differently, a customizable vendor will give you the bigger advantage.

3. Minimal Data Disparity

There is bound to be data discrepancies when you use several platforms (the ad server, exchange, DSP, etc.) together in an ad campaign. With every ad call from a DSP or publisher to the ad server, there will be slight data loss due to latency and other issues. As a general rule of thumb, the ad industry accepts up to 10% of data discrepancy. Anything more than that needs to be reconciled.

A reliable ad viewability vendor should have a dependable technology that keeps latency to a minimum while working towards achieving below 10% data discrepancy rate.

What is next for viewability & what this means for advertisers?

Viewability without a doubt will continue to be a growing metric more and more advertisers will adopt. It’s hard to predict the long-term effects of viewability but expect a firm viewability standard to be implemented.

We are also seeing more advertising budgets being moved from traditional media to digital media, embracing viewability as it has the potential to filter ad fraud and improve results for advertisers.

What’s important for you as an advertiser is to work with the right partner or vendor that is following the IAB’s recommended viewability standard and is transparent when it comes to reporting data measurement.

Additional Resources:
How to Measure Viewability Using MobileAds’ Audit Tool
How to Identify Bad Inventories in Display Ad Campaigns


Alvin is the Founder and CEO of MobileAds.com. He is a go-getter, and adventurous guy who believes in working smart to gain success in his business ventures and in life. He also founded RichMediaAds.com and MobileLanders.com.