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.
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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.
Example:
- 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 My Ads > Allow & Block Ads 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.