Google’s Gary Illyes says sticky footers on a website are nothing to worry about when it comes to SEO.
Illyes’ advice on sticky footers, which are footers that stay glued to the bottom of a screen, was prompted by the question of whether or not they can be seen as obtrusive.
In response, Illyes says one should always be cautious to not annoy users. That said, it sounds like there’s nothing against sticky footers in Google’s Webmaster Guidelines.
Nah, I wouldn't worry about that, but do try to make them as less obtrusive as possible. You really don't want to annoy your users
— Gary "鯨理" Illyes (@methode) July 28, 2017
However, there is one huge caveat here. If the sticky footer contains an ad then it could be frowned upon by Google.
According to the better ads standards, a large sticky ad which takes up more than 30% of the screen would be considered obtrusive.
“Large Sticky Ads stick to the edge of a page, regardless of a user’s efforts to scroll. As the user browses the page, this static, immobile sticky ad takes up more than 30% of the screen’s real estate.
A Large Sticky Ad has an impeding effect by continuing to obstruct a portion of the page view regardless of where the user moves on the page.”
Google has said it will block obtrusive ads in the Chrome browser beginning some time next year. This includes both mobile and desktop.
One may conclude from this that the sweet spot for a sticky footer is anything less than 30% of a screen’s real estate.
Since that will vary from screen to screen, it may be best to test your website design on a majority of today’s most common screen resolutions.