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Ad units

Ad size optimization setting

Let Google optimize your ad units on mobile

You can let Google automatically optimize the size of your ad units on mobile. There's no need to create new ad units or change your ad code. Your existing ad units will change their size based on the context and orientation of the user's device, and may show larger ads, full-width ads, etc. As a result, more ads will be eligible to fill your ad units, potentially leading to an increase in revenue.


This optimization setting only works on mobile-optimized sites and Accelerated Mobile Pages (AMP). In addition, we're unable to optimize in the following scenarios:

  • Iframed ad units (this includes ad units served through ad servers such as Google Ad Manager)
  • Ad units within a parent container that has restricted dimensions (e.g., a fixed height, overflow: hidden, etc.).
  • A user's first page view, because we use their first page view to get the ad size optimization setting from your account. For the user's subsequent page views, we apply your setting.

Preview automatically optimized ads on your site

You can preview the behavior of this optimization setting on your site before you turn it on.

On a mobile device

  1. Visit your site, and add #google_responsive_slot_preview to the end of your page's URL.
  2. Refresh the page.
  3. Toggle the orientation between landscape and portrait to see different ad sizes.

On desktop using the Google Chrome browser

  1. Open your site in a new tab, and add #google_responsive_slot_preview to the end of your page's URL.
  2. Toggle "Device mode" on. See Simulate Mobile Devices with Device Mode for instructions on how to do this.
  3. Select a mobile device from the drop-down list (e.g., Pixel 2 or iPhone 6/7/8).
  4. Refresh the page.
  5. Toggle the orientation between landscape and portrait to see different ad sizes.

These steps will be similar on other browsers. See your browser's documentation for more information.

Turn on the ad size optimization setting

  1. Sign in to your AdSense account.
  2. Click Ads.
  3. Click Global settings.
  4. In the "Ad size" section, turn on Let Google optimize the size of your mobile ads.

    Google will choose the best mobile ad sizes for you, based on what size performs best on your mobile traffic.

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