First things first, don’t display the same popup to mobile and desktop visitors.
In fact, using that same popup for both is exactly what could
get your site penalized by Google.Why, because when displayed on mobile, desktop popups tend to obstruct user experience by covering the content they wanted to read.
Just take a look at the visual below. It shows the types of popups Google considers too intrusive.
They cover most of the screen, and in the process, prevent a person from consuming the content they’ve come to the site for.
(Note, this problem is incomparably less severe on a desktop, where a popup covers only a fraction of the screen. Plus, you can position it naturally out of a person’s way.)
However, you can overcome this challenge by creating a mobile-only popup that meets Google’s quality criteria:
Using only a reasonable amount of screen space and being easily dismissible.
And the good news is, it’s not even that hard to do.
Our platform, for example, gives you the option to specify devices on which a popup will show.
See how it covers only a small portion of the screen, about 25% – 30%?
But specifically, what would be the acceptable size, then?
To calculate it, we need to first look at the most popular screen size. In Australia, for example,
most users have phones with screens at 750×1334 pixels.
Overall, however, the most common screen size is 780 x 1280, with a huge market share across multiple regions.
[Note: You can also establish the exact breakdown of popular screen sizes in your target market
here.]
And so, if we take 25% as the maximum height for your popup, then it should be no more than 320px high (25% of 1280 pixels)
In Australian market, you could probably create a slightly bigger popup, at 333px (25% of 1334 pixels)