Interstitial Ads

An interstitial ad is a type of ad placed on mobile devices that covers the screen, and can be dismissed by the user. You can identify an interstitial ad opportunity in the bid request by verifying that the Google protocol's field is set to true. For OpenRTB, the BidRequest.imp[].instl field is set to true in Protobuf or 1 in JSON.

Ad size

You can view a list of recommended ad sizes based on the width and height of the ad slot in the bid request. The device's screen width and height are passed in the BidRequest.device message of the bid request for both the Google and OpenRTB protocols.

Creatives aren't restricted to the recommended sizes in the bid request, but all recommended sizes in the bid request are guaranteed to be within the acceptable size range.

You can bid with any creative whose width and height meet the following criteria:

  • Less than or equal to the screen width and height
  • Greater than or equal to 50% of the screen width
  • Greater than or equal to 40% of the screen height

Screen dimensions are adjusted for notched devices and App Open ads. Make sure the dimensions in your response are withtin the acceptable size range.

If the ad size is too big or too small, the bid response is filtered with the rejection reason INTERSTITIAL_SIZE_MISMATCH.

If you don't specify the ad size in the bid response, the response is filtered with the rejection reason MISSING_AD_SIZE.

Sample bid requests

Here are some sample bid requests for interstitial ads.



OpenRTB Protobuf

Best practices

Google recommends the following best practices:

  • Include formatting attributes in your HTML creative snippets to center ads within the ad slot. Otherwise, ads render on the top left of the ad slot.
  • Respond with an interstitial ad that takes up as much space as possible within the ad slot. Don't fill an interstitial ad slot with a much smaller ad. For example, a 320x50 ad is too small for a 1024x768 interstitial slot.
  • An interstitial ad should cover the entire device screen.
  • Ensure users can close the ad:
    • A user can click the X button, added automatically by our SDK, at the upper right corner to close an interstitial ad. The publisher cannot auto-close an interstitial ad.
    • MRAID provides an API to close an interstitial ad.
    • Note publishers can't auto-close an interstitial ad. If a publisher doesn't accept interstitial video ads (for example, if they support display-only interstitials), the SDK automatically adds a close (X) button, even if you use MRAID useCustomClose().
  • Use the recommended sizes from the bid request to choose acceptable ad sizes for your bid response.
  • See the screen_orientation signal to choose creatives with the appropriate orientation.
    • On iOS, if the user holds the phone vertically when the request is made, then rotates the phone to be horizontal before the ad returns, the ad shows with black bars on the sides.
    • We recommend having vertical and horizontal creatives so you can bid with the appropriate orientation based on the screen_orientation signal.

Sizeless (fluid) interstitials

Sizeless interstitials (also known as fluid or responsive interstitials) dynamically resize to take up the entire screen width and height. Dimensions are adjusted for notched devices and App Open. Authorized Buyers doesn't resize creatives for you. You must supply a creative that dynamically resizes.

You only need to submit sizeless interstitials for review once, even though they can serve at multiple sizes. To ensure your creative isn't re-reviewed for each individual screen size, we recommend the following:

Bid response

  • Declare the SIZELESS_ADX, attribute 105 from the creative attributes, in your bid response.
  • Populate BidResponse.Ad.width and BidResponse.Ad.height with the size you want the creative to render based on ad size requirements, for example, 360x480 for a 360x480 screen size. The creative might still serve at other sizes.

If you add the SIZELESS_ADX attribute to an existing creative, the creative must be re-reviewed.

Creative pre-approval

  • When inserting a creative for pre-approval, include the SIZELESS_ADX attribute in the attribute field.
  • Submit the creative using a size that you expect to serve, that is, a common size for interstitial creatives. The creative can still serve at other sizes.
  • Each sizeless creative only counts against your creative limit once, even if it serves at multiple sizes.