Expand ads to fit device

Some ad slots are automatically expanded up to the maximum width allowed on a device. Experiments indicate that full-width creatives on mobile can outperform creatives that are narrower than the width of the device, potentially increasing your revenue. Ads fill a larger amount of the device screen and achieve a more natural fit within the content.

Example: If you have an ad slot of 300x250 and a device with a width of 360px, a 360x300 ad may serve.

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Ad slots eligible for expansion

Ad slot expansion currently applies to backfill display and out-stream video ad slots on mobile web. Not all ad slots are currently capable of expansion, though we’re working to increase eligibility.

How ad slot expansion works

It’s important to understand the difference between device width and container width:
  • Device width: The full width of the device screen (e.g., 360px on a Galaxy S8 and 375px on an iPhone 6).
  • Container width: The width of the box containing the ad, whose size is defined by the publisher’s web development team. On a mobile website, container width is typically the same width as the ad, the same width as the surrounding content (such as the paragraphs of text before and after the ad), or the full width of the device.

Ads may expand to the width of the device, while the height may increase proportionally when appropriate to preserve the aspect ratio. However, ad slots may not always fill to the full device width and/or expand in height. There may be times when ad slots:

  • Only expand to the container width. The container width is x, while device width is greater than x.
  • Expand by width but not height.
  • Don’t expand at all.

The ad slot will try to expand to fit the device width as long as it doesn't overlap existing content.

  • If overlap is detected with device width expansion, but not with container width expansion, the container width will be used.
  • If overlap is detected with both container width and device width expansion, the slot won't be expanded at all.

Control ad slot expansion

For Ad Manager 360 publishers, learn how to control ad slot expansion.

Examples of ad slot expansion

Original After expansion

More examples
Original After expansion
Original After expansion

Unified pricing rules and ad slot expansion

By default, Unified pricing rules applies to everyone and all sizes. However, if you have specified pricing for individual sizes, those rules can only be applied to requested sizes. This means if a request for an ad is sent and the ad expands to a new size, the new size will not necessarily have the pricing rule applied.


You've requested an ad with the size 320x480 with a device width of 400px and have two pricing rules. The first pricing rule targets ad size 320x480 and 1x1. The second rule targets size 400x600. 

Even if the ad expands to fill the 400px width, only the first pricing rule will apply due to an intersection with the targeted ad size. The second pricing rule will not apply.

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