How will Google’s mobile-first indexing affect SEO?

Google announced in March 2020 a complete change to mobile-first indexing for all websites, starting September 2020. Until that date, they will be moving sites to this type of indexation little by little when their systems recognize that those websites are ready.

The question is, what is mobile-first indexing and what does it imply for webmasters? We will solve all doubts in this post so you can know what to consider to avoid negative results on your website.

Mobile devices are being used more frequently by users. Therefore, mobile traffic for websites has been increased in a 30% from 2016. This is in some part due to the more accessible screens we have nowadays for this type of devices, as shown in the SimilarWeb report on Digital Trends.

Google has also taken into account past years tendencies and, seeing the increasing importance of mobile devices, they have decided to adapt their search engine technologies to users’ behaviour. This reflects on a focus on mobile searching and consequently, on this mobile-first indexing.

What is Google’s Mobile-First Indexing?

With mobile-first indexing, Google is using the mobile version of a web to index and compile results. In other words, your web’s mobile version will be the starting point for Google to index your content, and the base to calculate ranking factors.

Google’s bot will crawl websites as if searches were made from a mobile device, even when they are desktop searches.  Those websites using independent versions without taking into account the mobile content are at risk, as they may suffer a negative impact regarding its position and its organic traffic.

How has Mobile-First Indexing evolved over time?

From Google’s first announcement in 2016, when they started trying a new index centred exclusively in mobile devices, there have been several updates over the last years:

What is the difference between Mobile First Indexing and Mobile-friendly?

Despite both concepts are quite related, Mobile-First Indexing and Mobile-Friendly do not exactly mean the same.

Google’s mobile-friendly update (also known as the Mobilegeddon) in April 2015 penalized those webs that were not adapted to mobile devices. However, this was only applied in those searches made from smartphones, and for individual pages instead of whole domains. So those webs that were not optimized for mobiles and that had mainly desktop traffic were not really affected by this change.

This is water under the bridge since Google has decided that all searches will be mobile searches with this Mobile-First Indexing change. 

How do we know which user-agent crawls a website?

You can know which bot is using Google to crawl your website on Google Search Console. More specifically, you will find this in the Index Coverage report section. Here you will see if the main crawler is a desktop or a smartphone one, besides the last update.

Cobertura ordenadores

Cobertura smartphones

You can also see this information when checking any URL with this tool.

Inspeccion URLS

Can we switch our web to Mobile-First Indexing?

If your web is still being crawled on its desktop version and you are interested in change it to mobile because you consider this a better version, we are sorry to tell you there is nothing you can do. This is what John Muller says in the video, where he answers a webmaster’s question about whether Google is considering to allow a web being included in mobile-first indexing.

What happens if our web is not mobile-friendly and there is no mobile version?

With this change to Mobile-First Indexing, mobile versions are the reference when it comes to indexing and positioning. But there are many webs that may not be adapted to this type of devices. The desktop version is being considered a secondary option, though its content can be indexed too.

The fact that a website does not offer a good experience for mobile users can be an important disadvantage in contrast to other webs already adapted to mobile devices. This will have a negative impact on positioning, even for desktop search rankings, due to the fact that the default crawler will be a mobile one.

How can we be prepared for September 2020 Mobile-First Indexing update?

As we have already said, Google will start using the mobile version exclusively for web indexing and positioning. So, if mobile and desktop versions are equivalent, this change should not have a negative effect when it comes to search results.

In order to offer the best experience to users, Google has provided a guide of best practices emphasizing the fact that we must offer a desktop-mobile exact experience.

What we must take into consideration basically to adapt our web are the following features:


Make sure that the Google Bot can crawl all your web resources (images, CSS, JS files…) and process all your lazy-load content. Do not defer lazy-load main content that depends on the user’s interaction (like scrolling or clicks), as in this case the robots will not load it.

Check that you are not using the disallow command in the robots.txt file. This will prevent the crawling for some parts of the web that are important for positioning.

Meta Tags

According to Google, we must use the same robot meta tags for both versions. So be careful with noindex and nofollow tags in your mobile version, as those URLs will not me crawled or indexed this way.

Identical content

Desktop and mobile versions must be identical. In case you have less content for your mobile version, you must change this. Google will not obtain the same information of your website after activating Mobile-First Indexing by default, which will derive on less traffic. It is even recommended to use the same headings for both versions so content cannot be considered different. This also applies for metadata: use equivalent titles and meta descriptions in both versions.

Structured Data

Make sure your structured data is present in both web versions, with no differences.

You will find all these recommendations and many more in Google’s guide of best practices, so have it in mind to adapt yourself to this new change.

To Conclude

Now you know. Mobile First Indexing is coming. In September 2020 all websites will be crawled with Google’s smartphones user-agent.

As long as your web mobile-responsive and content is equivalent in both versions, there is no need to worry. This update will not mean an important change when it comes to web performance.

If on the contrary, your web has a Dynamic Serving mobile configuration or independent URLS with different code for each device, try to make those necessary changes to update your web to this new way of indexing.

Anamaria Vaduva

SEO Specialist

Apasionada del SEO y adicta al buen chocolate. Me gusta aprender cosas nuevas todos los días, la curiosidad es mi naturaleza. Entre SEO y mis niños, a veces me queda tiempo para ver alguna serie en Netflix.

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