Earlier, AdSense had a maximum limit of 3 ad units (while “premium partners” enjoyed serving up to 6 ad units).
In August 2016, AdSense lifted the ad unit limit for every site.
- You can now place an unlimited amount of AdSense ads on a page.
Google has lifted the limit restrictions. As long as your ads do not exceed your content, there is no upper limit on the number of ads on a single page.
It’s important to note that while picking the number of ads, you should think about the short posts on your blog. If you decide to place more than 5-6 ad units, and you are placing them sitewide using a plugin, you might be spamming your own short posts with a large number of ads.
AdSense has explicitly mentioned:
“We may limit or disable ad serving on pages with little to no value and/or excessive advertising until changes are made.”
So I suggest you keep less than 5 ads per page.
I usually stick to 3 or 4.
But you should identify your own limit according to your blog’s layout.
A few things which I have learned from my own experience:
Sometimes 2 ad units perform better than 3 ad units.
Placing ads above the fold yields better results.
A combination of image + text ads perform better.
There are many different options available for the placement of ads, but I highly recommend using a minimum amount of ad units or utilizing adverts only at the bottom or on the sidebar.