In the past, there was a limit on the number of ads you could place on a single page:
- 3 ads for content units
- 3 ads for link units
However, in august 2016, Google updated their policy (read about it here).
To sum up, if you don’t want to read too much, the new idea is this: “you can place any amount of ads on your page as you want, but don’t overdo”.
In more correct terms, they state that “Advertising and other paid promotional material added to your pages should not exceed your content”
How should we interpret this?
The way I see it, they are saying “don’t have more ads than content”. Which makes sense, given that a page with more ads than content would not be so nice.
So don’t over do it, use your common sense, and you will be fine.
Ah, since they are not giving you a specific rule (like in the past, the maximum was 3, which is something really specific), keep your account safe, so when in doubt, have one less add than you would (you wouldn’t want the big G to ban your Adsense account).
For example, I wouldn’t have more than one unit visible on a mobile device (that can be interpreted as “more ads than content”. On a large desktop site, 2 or even 3 visible might be just fine (and I say might because you never know with those Google people).