The Oracle Data Cloud blog highlights the latest data-driven insights and trends in digital marketing and ad tech.

What’s the optimal size for a mobile ad?

This week’s guest blog post is contributed by Brian Barwick, Account Manager, Oracle Data Cloud.

The average consumer’s smartphone screen has become precious real estate. With more than 1.5B smartphone sales annually across the globe, and the large increase in time spent by adults on mobile devices over the last decade, the marketer’s battle for user attention is now squarely centered in the mobile world.

Marketers deserve a better shot at reaching attentive mobile audiences, and mobile audiences deserve a better site experience. We believe both of these can be addressed by taking a close look at how different inventory can grab consumer attention; for many, that means rethinking the mobile 300x250 banner ad.

But as growing pains across the digital publishing ecosystem increase—including limited insights into viewability and user attention—publishers and advertisers alike have yet to crack the formula for successful mobile-forward advertising. One key drag on their success is the antiquated reliance on the 300x250 banner ad, the ubiquitous industry standard designed for a desktop-first world. 

On traditional desktop, a 300x250 ad size makes perfect sense. Publishers have leeway to structure their pages and deliver quality content without an overly intrusive ad layout. And advertisers get a standardized chunk of potentially valuable screen real estate. With the advent of mobile, the industry chose not to reinvent the wheel and transferred the reliance on 300x250 to the mobile environment, which led to mixed results for publishers and advertisers.

While hindsight is 20/20, these mixed results are relatively intuitive when you think about how we use our smartphones for consuming online content.

1) Users visit websites specifically for a content-first experience

Mired in the complex world of digital advertising, this point is often lost on many of us: for the typical visitor, ads are an afterthought. Publishers no longer have the luxury of the right rail (the right side of a web page where ads and links to more content lives) and instead have to increase their reliance on placing ads in-line with the content.

2) Drastic reduction in screen real estate

Compared to the size of the screen itself, a 300x250 screen ad barely leaves room for a few lines of an article. Presupposing, again, that visitors are there for the content, there is no incentive for them to keep a meaningful chunk of the ad on their screen.

Additionally, publishers must face the challenge of fitting all of their ads into this condensed space, leading to a stacked ad experience far below the fold.

Viewability should be key for advertisers

As everyone in the industry is keenly aware, viewability can make or break a campaign. With conversations shifting focus now to the quality of a viewable impression, it’s incumbent on publishers and marketers to review what units on mobile are most likely to spark attention and engagement with an ad.

Look to the data

Each quarter, Moat collects data on trillions of impressions run across the web, which we use to create a comprehensive set of global industry benchmarks. In our latest round (Q1 2018), you can see a drastic difference in performance between the 300x250 ad’s mobile performance and a unit designed specifically for the mobile ecosystem—the 320x50.

For a baseline comparison, the 300x250 has an average in-view rate of 42.8%, compared to 60.6% for the 320x50.

Considering user behavior combined with the Media Rating Council’s (MRC) one continuous second requirement for a viewable ad, these smaller ads are more likely to be deemed “viewable.” Beyond that, however, they also are more likely to get coveted user attention.

The 320x50 has an average 50% on-screen time of 15.4 seconds. That is almost double the 5.4 seconds of the 300x250. In fact, the in-view times of the 320x50 grow exponentially higher than the 300x250s, starting at 2x for 15 seconds and reaching as high as 8x at the 1-minute mark.

User Attention by Ad Format, Moat Q1 2018 Benchmarks


300x250 Mobile Placements

300x50 Mobile Placements

15 Second In-View Time



60 Second In-View Time



Mobile advertising bottom line

Of course, there is an inherent tradeoff in trafficking fewer 300x250 units in mobile in terms of screen real estate. You can fit more into those bigger units. However, the ad’s real estate is the exact reason it spends so little time on screen.

Paradoxically, something designed specifically to be more noticeable is actively being ignored.

As the previous chart shows, today’s publisher needs to closely analyze the data they have and not rely on commonly held assumptions, e.g., bigger is better when it comes to viewability. For those publishers currently faced with the task of improving their site’s overall viewability, it’s incumbent to understand that different ads have a different impact on mobile users.

Make sure you check your performance, compare ad sizes and device types, and determine if you should reconsider your mobile advertising strategy.

Contact The Data Hotline today to learn how Moat’s viewability insights can help your brand. (What's The Data Hotline?)

About Brian Barwick

Brian is a sell-side Account Manager at Moat, an analytics and advertising measurement firm in the Oracle Data Cloud.

Prior to Moat, Brian began his career in the gamed WME mailroom before helping manage the builds of some of the web’s fastest-growing digital properties at RebelMouse.

Stay up to date with the latest in data-driven news by following @OracleDataCloud on Twitter and Facebook.

Keep in the loop by following Moat on TwitterLinkedIn, and Facebook.

Image: Shutterstock

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