On Twitter, Google’s John Mueller confirmed that the hreflang attribute should be configured as mobile-to-mobile and desktop-to desktop. The hreflang attribute is used for language and regional URLs.
What is the hreflang attribute?
Many websites serve users from around the world with content translated or targeted to users in a certain region. Google and other search engines uses the rel=”alternate” hreflang=”x” attributes to serve the correct language or regional URL in Search results.
Twitter user Aleyda Solis posted a chart to clarify what should be done for the mobile-first index:
@methode Hi Gary! I wanted to confirm the hreflang configuration update in mobile URLs mentioned during your Pubcon session that @jenstar tweeted here: https://t.co/oi53IBElta – the update would be like shown in this image or something else? ? Thanks for the clarification! pic.twitter.com/4oIl6WTiMJ— Aleyda Solis (@aleyda) November 26, 2017
Responsive websites work best
John Mueller also said that you don’t have to worry about this if your website uses responsive website design:
If you have a responsive site, you don't need to do anything special. The URLs are the same on desktop & mobile. Easy ?— John ☆.o(≧▽≦)o.☆ (@JohnMu) November 30, 2017
If Google can index your web pages correctly, your website will get better rankings. The tools in SEOprofiler can help you to to this: