A recurring question from AdSense publishers using our Advanced Ads plugin for WordPress is how to stop AdSense from showing ads being smaller than the actually ad unit. This article explains why this happens at all, what you can do about it and whether this actually is in your interest or not.

Why does AdSense show smaller ads?

Showing a smaller ad in an ad unit you defined might seem like a waste of resources at first. However, this is in fact a feature of AdSense called Similar-sized ads. This simply means that AdSense can show an ad (creative) that was originally set up by the advertiser to have another size than the ad space you defined on your site.


  • 300×250 (Medium Rectangle) showing up in 328×280 (Large Rectangle) space
  • 468×60 (Full Banner) showing up in 728×90 (Leaderboard)

Why does AdSense do this?

Simply, because it increases competition. The more ads can be potentially display on your site, the higher the competition and the higher the price you will actually get per click or impression.

The downsize of showing an originally smaller ad in a larger space is that it leaves space unused left and right to the centered creative. More about this below.

AdSense resizes larger ads to fit as well

What many publishers don’t know is that also ads that were originally set up to be larger can fit into smaller ad units. E.g., AdSense can resize a Leaderboard (728×90) to fit into a Full Banner (468×60). AdSense does this for the same reason: increasing the competition for you to make more money.

Showing larger ads does not need more space. It will simply be resized to fit into the ad units size you defined.

How to stop smaller ad sizes in AdSense?

You can simply switch off the similar-size feature in your AdSense account. But be warned: this switches off all resize features for all ads. There is no ad-specific setting for this.

Go to Allow & Block Ads > All my sites and click on the Ad serving tag.

In the Display ads section, you will find the Similar sized display ads option right at the top. I switched it off in the example on the screenshot, but it is on by default.

AdSense similar-size option

Should I prevent AdSense resizing ads?

The question that can literally be worth millions is whether you should switch off similar-sizes or not.

I think you shouldn’t. Having only ads displayed that perfectly fit into your ad units might cut the competition to only a fraction and decrease your ad revenue from AdSense a lot.

I have not yet met a publisher that had a good argument to do this in my work as a consultant or with our Advanced Ads plugin.

Can the empty space collapse automatically?

It might be a smart idea to just collape the space left unused if a smaller ad is displayed. However, due to the method AdSense uses to deliver ads and how it predefines the space it is not possible to automatically collapse the size.

Instead, if you want an ad that only takes the available space, take a look at the Responsive ad units from AdSense. They have their flaws too, though.

Let’s just assume there is a way to collapse the unused space automatically in the near future. This might be irritating, too, because it would cause the already loaded content around the ad to move by the collapsed space again.

Reports for Creative sizes

If you like the AdSense performance reports as much as I do, you will be interested in this: Asside from the normal Ad sizes report, there is one called Creative sizes, too. This report contains the sizes of the actually delivered ad sizes, not the ad unit sizes which you defined.

You can combine your ad specific report with the Creative report to see the ad sizes actually delivered to a specific ad.

Use this to see if there are really many smaller or larger ads delivered. If you still think there are too many “wrong” ad sizes used, you can switch your ad units to another size based on this report without losing too much of its performance.

The Author


  1. kazonkiza whiteley

    Thanks for such a deep insight on preventing adsense to showing smaller ads, it will dentally helps me, Thank 🙂

  2. kundan

    Most of the ads displayed on my site are same. One Ads getting displayed twice reduce the CTR, is there way to stop showing same ads again in one post.

    1. Thomas Maier Article Author

      Is this the same ad code or only the same ad content? As for the latter, there is no method I know of to stop AdSense from doing that.


    Thanks for developing amazing plugin.

    Can I use this plugin on amp pages? If not, please suggest me some good plugin for my website.

  4. Akshat

    I have seen on blog too that adsense sometime shows smaller dimensions ads. Now i know why and how to change it. Thanks

  5. Oukitel

    I guess there is nothing anybody can do about that. Like you said, responsive ads have there own flaws and may not be the best option for some people.

  6. Matthew

    Your guide needs updating.

    There is no such path as Go to My Ads > Allow & Block Ads and you can’t do anything from a “Ad serving” tag.

    Allow and block ads is now found under its own tab but there is nothing in here that allows for enabling or disabling of such a feature.

    1. Thomas Maier Article Author

      Thanks, Matthew. You are right. This option is now in Allow & Block Ads > All my sites.

      1. Shiv

        Sir my site’s primary language is english. Still adsense is showing ads related to different languages like french, german etc most of the time. Why not in english??

        1. Thomas Maier Article Author

          While I don’t know the exact details, AdSense can use a lot of other information to show ads. Maybe you visited German sites before, or your browser language also allows German. The fact that you see non-English ads does not mean that your visitors also see them.