MRC Viewability Standards: A Quick Reference Guide

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Almost a decade ago, the Media Rating Council (MRC) rolled out new standards and began conducting audits to ensure that digital advertising was both reliable and effective. 

The MRC is a well-known independent organization in the ad tech world that emerged out of the need to make the entire industry better for advertisers and publishers alike. That means everyone within the ad tech world must agree upon and follow the MRC’s ad viewability standard—which is essentially a standard designed to determine whether an ad impression is viewable or not viewable. 

Ad viewability is essentially a pain point for everyone within the ad tech world. However, it wasn’t until the publishers and advertisers started to understand the impact of viewability in regards to their bottom lines that it became obvious that there was a need for a standard to be created that would allow them to measure an impression’s viewability.

In this article, we’re going to tell you everything you need to know and understand about the MRC viewability standards so you can ensure you’re following them and ensure that they’re viewable.

Read on to learn more.

What Is MRC Ad Viewability?

So, MRC set forth by defining certain thresholds to help the ad tech world determine whether or not an ad impression in question could be considered viewable. Of course, in defining those thresholds, the MRC has to take into account two very important concepts:

  • Fraudulent and invalid impressions which are both considered illegitimate ad impressions, generally speaking. These impressions are usually generated by botnets, artificially manipulated page loads, and so on. Their entire existence is contingent on draining ad dollars from buyers garnering invalid traffic.
  • Viewable ad impressions which are considered viewable when the ad is placed in the viewable space of a web browser’s window. If the ad in question gets displayed outside of the browser’s viewport, then the impression won’t get the chance to be seen by the user. Therefore you could say that viewability really depends on the placement of an ad impression.

There are also two types of ad viewability—display ad viewability and video ad viewability.

MRC Display Ad Viewability

According to the MRC guidelines, a display ad is only considered to be viewable if at least 50% of the ad creative is clearly visible for at least one second within a browser’s viewable space. Additionally, an ad impression can only be counted as viewable under the following requirements:

  • There must be a significant interaction between the user and the ad for the ad to be considered viewable—even if it doesn’t meet the time or pixel requirements. When we say a significant interaction, we’re talking about a purposeful click on the ad by the user. For example, hovering the mouse cursor over the ad wouldn’t count as an impression.
  • Viewability is technically counted in two ways—viewability vendors will calculate the number of viewable impressions based on a single ad using a JS tag code. Other vendors calculate the impressions by measuring the ad container (iFrame) in which the ad is set to appear. As measurement based on iFrame containers is considered acceptable as long as the ad appears in the appropriate format.  
  • For large ad display sizing, for example, 242,000 pixels (970×250 display ads) or greater, a minimum of 30% of the pixels within the ad must be visible on the viewport of the page for longer than one second. Otherwise, it won’t be counted as viewable.
  • For rich media display ads which typically appear in smaller sizes and expand based on users’ actions, viewability is measured based on the pixel count of a smaller format of the ad or the expanded format of the ad. When based on pixel count, viewability is measured by both the ad view time in its pre-expansion state as well as during its expanded state. If the ad is regarded as viewable in its expanded state, then the view time only counts once.

If the website pages are pre-fetched or pre-rendered, then the delivered ads to those pages won’t be considered as viewable ads until the ad appears within the viewable portion of the browser and proceeds to follow the requirements listed above.

MRC Video Ad Viewability

According to the MRC guidelines, video ad impressions will only be counted if 50% of the pixels in the ad are visible in the viewable space of the browser for a minimum of two seconds. However, those two seconds will only be counted for the first two seconds of the ad, which means that the user would have to have seen the video ad from the beginning.

There are also a few other considerations for the viewability of video ads, such as the conditions that meet the MRC ad viewability requirements. They’re very similar to the display ad guidelines, with the following exceptions:

  • For Click-to-Play video ads, once a video is initiated by a click, 50% of the ad must be in view for the first 200 milliseconds for the video ad to be considered viewable.
  • For Auto-Play video ads, it is up to the third-party vendors to measure and report the viewability appropriately as it’s difficult to determine whether auto-play ads are viewable once they start. 

Using Metrics to Define the MRC Viewability

The MRC has defined three different metrics to help measurement partners, advertisers, and publishers measure their viewability and ad impressions count. These metrics are calculated as follows:

  • Measured rate: Measured rate = viewable impressions + non-viewable impressions / total impressions served
  • Viewable rate: Viewable rate = viewable impressions / viewable impressions + non-viewable impressions
  • Impression distribution: Impression distribution represents the percentage of all viewable, non-viewable, and undetermined ad impressions

The purpose of these metrics is to measure the overall organization and performance of the ad impressions. The goal is to determine how many ad impressions are, in fact, viewable and how many are not. 

Final Thoughts on Ad Viewability

Despite the MRC guidelines and metrics, measuring valid ad impressions is still very difficult. Viewability remains a major challenge in the ad tech world, which is why it’s recommended to strive for 70% viewability as per the above guidelines to ensure optimal CPMs.

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