ad sizes

Top tips for optimizing your ad sizes in 2019

Your website may look fantastic with a 970x250 banner ad, but it may not be the best size for monetization. Optimizing ad unit sizes based on advertising demand can be a quick and easy way to increase yield.

Buy-side partners pay for ad space that meets the needs of their buyers' creative assets. Buyers decide which ad unit sizes to build assets for by assessing where there is healthy inventory for fill. What this means is that when an ad unit size is less common, for example a 970x250 ad, there will generally be less demand for it, and potentially lost revenue. Optimizing the ad unit sizes on your site with ones that are in high demand is a simple way to open up your site to all of the demand available.

See Figure 1 for the most common ad sizes in Sortable's network for desktop web traffic. While you may get a higher CPM for an ad that is 970x90, the fill rate could be far lower, which could result in less revenue.

Figure 1
Desktop Web Ad Size Traffic vs. CPM - September 2018


Due to the large amount of screen real estate on desktops, there are numerous different ad layout combinations to choose from and consider in order to optimize yield. Individual analysis and consultation is needed on a site-by-site basis.

For mobile web ad sizes and layouts, choices are more limited as there is a much smaller amount of screen space. See Figure 2 for a comparison of the two main ad sizes by impression volume, 300x250 and 320x50.

Figure 2
Mobile Web Ad Size Traffic vs. CPM - September 2018


The 300x250 ad unit size has been around since long before mobile browsing started, so when the mobile revolution began there was already an abundance of 300x250 ad demand available. This created a self-fulfilling cycle”publishers converge on certain ad sizes, which causes advertisers to create more ads for that ad size, which increases the available demand for that ad size.

Equally important to ad sizes on mobile is the layout of the ad placements. Due to there being a much smaller screen size on mobile devices compared to desktops, there is a fairly defined set of ad layouts which are possible. We recommend against placing a 320x50 ad at the top the page (A), as data clearly indicates that this ad slot is very rarely viewable. Users often immediately start scrolling down the page to read content. By the time the ad slot has loaded, the ad is out view.

Adhering to Google's rules of only one ad above the fold (ATF) on mobile, the most profitable display configuration on mobile is one where a 300x250 ad is placed within the body content, so that it is 50% viewable above the fold (B).


When determining which ad size to display, the answer isn't always as simple as putting in the largest size that will fit. Using a size that is not very popular could negatively impact CPM or fill rate. Optimizing for ad size is key to maximizing your revenue.

Sortable's ad ops experts are available to consult on the best possible ad size and which locations would be most likely to boost your revenue. In addition, Sortable's analytics platform allows you to perform tests to determine the best layout to maximize your profits.

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