Google Starts "Mobile First" Indexing

Different Approaches To "Mobile-Friendliness"

Before the invention of tablet computers and the corresponding increase in the number of screen sizes available, most websites catered to mobile devices by having a separate website that was designed solely for them - usually accomplished by having a separate domain (For example, ""). This approach had some significant disadvantages, including the fact that any links to a company's mobile-only website would not benefit the desktop-only website and vice versa. Now, most websites use "responsive" web design, meaning that the same website is displayed to all users, but that the website responds to the various screen sizes being used by changing it's layout.

Google's Problem With Different Mobile And Desktop Website Versions

Most Google searches are now performed on mobile devices but, where both a mobile- and desktop-version of a website exists, Google's ranking systems still use the desktop version of websites to decide how relevant a page is to the user's search. This can result in search results on mobile which disappoint the user because mobile-only versions of websites commonly contain less content than their desktop equivalent. That is, the user is less likely to be returned search results that provide exactly what they are looking for.

To counter this, in late 2016 Google announced that it had started experimenting with a "mobile-first" philosophy, whereby it will use the mobile version of websites to evaluate their relevance to search terms instead of the desktop version, regardless of the device used. This was a significant change, and one that would inevitably graduate from an experimental stage into Google's core algorithms. At this stage, Christi Olson from Bing says that they currently have no plans to emulate this approach.

How This Change Affects You

Here's how this change to Google's approach will affect you, depending on which of the following three scenarios your website falls into:

  • You operate separate mobile and desktop versions of your website: This change may have a significant impact on your search engine rankings. Your rankings might drop if your mobile-only version contains less content than your desktop version, and if less websites link to your mobile version than your desktop version. Google announced in June 2018 that despite the fact that indexed content will always be the mobile version, the desktop URL will be displayed on searches performed on desktop and vice versa. In March 2019, Google's John Mueller confirmed that he thought websites with separate mobile and desktop URLs should move to a responsive website design instead.
  • You only have a desktop version of your website: This change is likely to mean that your website's search engine rankings will suffer even for searches performed on desktop computers. And since mobile-friendly websites rank higher on searches performed on mobile-devices, you really should consider upgrading your website to be mobile-friendly.
  • You have a responsive website: Congratulations - in this case this change will not affect you and you don't need to change anything. Even if your website's layout changes on mobile devices (for example if some navigational elements become hidden),if these changes are purely to enhance the user experience on mobile devices such elements will be given full weight.

Interestingly, if your website uses Accelerated Mobile Pages (AMP) (in any of the three cases above),Google will not treat them as your website's default mobile version. This means that for optimal search engine rankings your non-AMP content still needs to be mobile-friendly.

When This Change Is Likely To Happen

Google first announced their intention to transition to a "mobile-first" index in November 2016, but have regularly delayed the transition. In March 2020 Google announced that 70% of all websites were now included in the "mobile-first" index and that all websites would be included by September 2020. But then in July 2020 they changed this deadline to March 2021 and then finally declared that it had been indefinitely postponed in November 2021. The statement said that Google has determined that some sites "are still not ready to be shifted over due to various, unexpected challenges" and that therefore the timeline would be left open for the last steps of the transition. You can check to see if your website has already been switched to "mobile-first" indexing by checking the settings page for your website in Google's Search Console.


Luckily, most websites built within the last few years will have been built responsively. But if your website is not yet mobile-friendly, or your website has both mobile and desktop versions, it's time to act before your website is left behind completely in the search engine rankings. And if you are not sure which of the above scenarios your website falls into, please leave a question below or Contact Us for a consultation.

Last updated: 30th November, 2021