Google’s Mobile-First Indexing Update: Everything You Need to Know

Google's Mobile-first Indexing Update - Hero Image

Three in four smartphone users use their phones first in order to address their immediate needs. 

If you want to be able to respond to these needs, you need to think mobile. Mobile-first.

And Google’s response was to introduce mobile-first indexing.

This article will describe everything you need to know about this update. I will guide you through what mobile-first indexing means, why Google decided to introduce it, and what will change in the way your website is crawled and indexed.

I’ll also outline the necessary steps that you need to take to win in the mobile-first world. 

Wondering what mobile-first indexing means? Let’s dive in.

What is mobile-first indexing?

With mobile-first indexing, websites are crawled, indexed, and subsequently ranked by Google based on ranking factors collected from their mobile versions. 

The goal of the mobile-first indexing update is to switch to a fully mobile-first index. When this change goes live, all websites will be primarily crawled by the mobile Googlebot, and it’s the content that’s visible on mobile that will be indexed. Any ranking signals ranging from page titles to internal links will be collected from the mobile version, too.

So your website’s mobile version is going to be the main source of information about your domain for Google, and it will determine your rankings.

It’s important to know that Google doesn’t want to create separate databases for mobile and desktop.

Google has been gradually switching to a fully mobile-first index since 2016. Most websites have already been switched over – Google’s algorithm has been detecting which websites are ready for the transition and automatically switching them to the mobile-first system. 

Google was planning to have all websites moved to mobile-first indexing by the end of March 2021. However, during the analysis of the pages that still hadn’t been switched, Google determined that for various reasons, some of them are still not ready to move to mobile-first indexing. The search engine decided to cancel the deadline and continue gradually switching the remaining sites.

How were mobile sites treated by Google in the past?

Previously, Google treated the desktop version of a website as the ‘canonical’ one, while the mobile version was viewed as the ‘alternate’. So all websites were primarily crawled by the desktop Googlebot and Google wanted to index the desktop content first and foremost.

Here is a quick breakdown of what exactly is changing in the shift to mobile-first indexing:

  • In the case of mobile-first indexing, it’s the smartphone Googlebot that is taking care of the crawling process and it will also crawl sites that aren’t mobile-optimized. That being said, Google had been conducting tests that showed that most websites are actually ready for the transition
  • If the content you have on mobile varies from the desktop version or, for any reason, you choose not to have some of it on your mobile version (it’s a really bad idea!), now is the time to fix it. 
  • Anything that’s missing on the mobile version will not be indexed, and will not get you any traffic. Content that Googlebot can only access on the desktop will be ignored.

Why was introducing mobile-first indexing necessary?

Mobile-first indexing is Google’s response to rapidly shifting user behavior trends.

Mobile traffic has been on the rise for years as browsing the web on mobile devices became a fundamental element of everyday life.

In terms of the market share measured per device worldwide, desktop and mobile devices had been competing steadily until mobile took the lead after May 2019. Since then, the disparity between mobile and desktop devices continues to grow. As of January 2021, the gap has deepened, with mobile accounting for 55,68% and desktop for 41,45% of searches, accompanied by 2,87% of searches on tablets. 

At the end of 2013, 34% of all searches on Google were made from mobile devices. By the end of 2019, this percentage had increased to 61%

The number and specificity of searches vary across industries. A study concerning the period up to May 2019 found that searches related to topics concerning some central industries in the United States came predominantly from mobile devices. For instance, out of all searches in each industry, 68% of food & beverage, 65% of automotive, 62% of health & medical and sports, and 61% of gambling-related queries came from mobile devices. 

Switching the focus to mobile sites is more urgent for those whose industry receives more mobile searches. 

How could these numbers impact you and your website?

SEMRush published an insightful research study concerning SERPs across mobile and desktop devices and how these may potentially deviate.

SEMRush pulled out statistics on how many websites lose their desktop positions in mobile searches. They discovered that only 13% of websites maintain the same results across various devices.

What is particularly significant is the disparity between Top 10 results across different devices – over 30% of URLs lose their visibility on mobile. 

Of course, the fact that not all websites are optimized to perform well on mobile devices could play a role here, but there can be additional factors that have an impact on these results. 

For instance, Fernando Macia sees some of the possible causes for this in the importance of geolocation that varies across desktop and mobile devices, as it is much more relevant on mobile and gives a higher chance for local results to appear. 

Google says that having mobile-first indexing applied to your website and being crawled by the mobile Googlebot does not directly influence your rankings and will not decrease your position. It’s the state of your website that can impact these rankings and whether your competitors have already optimized their sites for mobile Googlebot.

What do we learn from this? First and foremost, optimizing for mobile devices is no longer just an option but something that should become a priority. 

Is it enough to have a mobile-friendly website?

Having a mobile-friendly site is an important step in ensuring your website provides a good experience to users, regardless of the device they’re using. 

Unsure whether your site is mobile-friendly? Take Google’s Mobile-Friendly Test and find out!

But remember that having a mobile-friendly website doesn’t mean it will do well in response to the mobile-first indexing update. 

You should audit your entire website and check if any important content is missing on mobile. 

Google and mobile-first index: Changelog

Although our search index will continue to be a single index of websites and apps, our algorithms will eventually primarily use the mobile version of a site’s content to rank pages from that site, to understand structured data, and to show snippets from those pages in our results.
source: Google
  • Google then provided a follow-up in December of 2017, giving additional guidance. They indicated that they want to help the increasingly mobile community of users to find what they are looking for and in the form that would respond to their needs. Moreover, they informed everyone that:

Webmasters will see significantly increased crawling by Smartphone Googlebot, and the snippets in the results, as well as the content on the Google cache pages, will be from the mobile version of the pages.
source: Google

Google also introduced some specific points that developers should be looking into and clarified that this change will be rolling out slowly and cautiously in order to give everyone time to prepare. They began evaluating sites that were ready to be included in mobile-first indexing based on the introduced criteria.

Mobile-indexing is rolling out more broadly. Being indexed this way has no ranking advantage and operates independently from our mobile-friendly assessment.

Having mobile-friendly content is still helpful for those looking at ways to perform better in mobile search results.

Having fast-loading content is still helpful for those looking at ways to perform better for mobile and desktop users.

As always, ranking uses many factors. We may show content to users that’s not mobile-friendly or that is slow loading if our many other signals determine it is the most relevant content to show.

source: Google
  • Another update came in the blog post from December 19, 2018, that acknowledged the mobile-friendliness of a lot of sites but pointed out that webmasters should dedicate more attention to structured data and including alt tags in images in particular. 

Though content accessible only on the desktop version would not be used in the index, websites without a specific mobile version might still be visible in search results, as Google assured us. 

From our analysis, most sites shown in search results are good to go for mobile-first indexing, and 70% of those shown in our search results have already shifted over. To simplify, we’ll be switching to mobile-first indexing for all websites starting September 2020. In the meantime, we’ll continue moving sites to mobile-first indexing when our systems recognize that they’re ready.
source: Google
  • In November 2021, Google publish a blog post explaining that some pages are still not ready to switch to mobile-first indexing and decided not to set up a new final date:

Earlier, we thought that we could complete the move to mobile-first indexing by March 2021. However, we found that some sites were facing unexpectedly difficult challenges and we wanted to accommodate their timelines. We currently don’t have a specific final date for the move to mobile-first indexing and want to be thoughtful about the remaining bigger steps in that direction.
source: Google

Mobile-usability vs mobile-first indexing

With mobile-first indexing, the content that mobile Googlebot can crawl and access will be shown in the search results index. This doesn’t mean that the content is mobile-friendly – it can still be difficult to navigate by a mobile user. 

John Mueller spoke about this specific issue during Google Webmaster Central Office Hours on January 19, 2019:

An extreme example, if you take something like a PDF file, then on mobile that would be terrible to navigate. The links will be hard to click, the text will be hard to read. But all of the text is still there, and we could perfectly index that with mobile-first indexing.
source: John Mueller

So, taking a user-driven and mobile-centered approach is definitely beneficial, but it’s not mandatory in order to be included in the index.

How to check if your website has been switched to mobile-first indexing?

If your website was created after July 1, 2019, it’s been automatically indexed based on the mobile version. Mobile-first indexing is applied to new websites by default.

If your website is older, you can use Google Search Console to check whether it was already switched to mobile-first indexing. Under settings for a GSC property, you’ll see the crawler Google is using to crawl and subsequently index your site.

Opting in or out from mobile-first indexing

It’s not possible to opt-in or out from being included in the mobile-first index. So you can’t tell Google not to apply this to your website but also you can’t directly submit it for being included in the update faster. 

Google’s mobile-first indexing: Best practices 

Now that you know what mobile-first indexing is, let’s talk about what you can do to get your website prepared for it.

Google provides a detailed guide with some best practices to follow with regard to mobile-first indexing.

We will look into them together now to ensure your visitors enjoy being on your website on all types of devices.

Make sure that your mobile version provides the same user experience as the desktop version.

The primary content on your mobile site should be equivalent to what can be found on the desktop site. If your mobile site has less content than desktop, Google won’t be able to access some of your site’s information with mobile-first indexing. This can negatively impact your traffic. If the content is equivalent across both versions of your website, but there are differences in their DOM or layout, Google may understand their content differently.

Write your copy with mobile-friendliness in mind

Adjust your copy for mobile devices by dividing the text into more paragraphs and write shorter sentences. Your headlines should also be sending the same message across all devices. Check if your font is large enough to be visible and readable on a device with a smaller screen. No zooming or moving around should be required to read your text. 

Make sure your structured data is the same across both versions

Not only should structured data be present on mobile and desktop pages, but the markup should be constructed accordingly and correspondingly. Using relevant structured data for your mobile site is crucial in helping Google understand the content on your website.

Adjust metadata for both versions

Verify whether your metadata, such as titles and meta description, are equivalent on both types of devices. They do not necessarily need to be 100% the same and follow the same word-by-word order, as the character count is not equal, but they should convey a similar message – and do not omit your keywords. 

Ensure the contents of your mobile site can be accessed and rendered

Use the same meta robots tags on the desktop and mobile versions so it’s clear how your site should be crawled and indexed. Keep in mind that Google will not be able to access content that requires user interactions to load, such as swiping, clicking, or typing. Implement lazy-loading for your content correctly so that no content remains hidden, but instead, all is visible when in the viewport. 

Check your images and videos

Your images and videos should be crawlable for Google. Use alt text for your images. Use a supported format for your pictures and videos and ensure the images are high-quality, not blurry or in low-resolution. Don’t use constantly changing URLs for your images or videos. You’ll find more actionable advice in Google’s images and video guidelines.

Check ads and interstitials

Accessibility is particularly relevant on mobile screens as they are smaller than on desktop devices. That is why you need to triple-check that no popups, ads, or intrusive interstitials are covering the content on your website, making the experience troublesome.

If you absolutely need to display interstitials, Google offers a guide on interstitials and best practices concerning their placement on a website.

Monitor and optimize page speed

Page speed is a crucial metric for all types of devices but it’s particularly critical when it comes to mobile devices. 53% of users abandon mobile sites that take more than 3 seconds to load. Your mobile user will expect that your site loads as quickly as the desktop site. Not to mention that page speed is now one of the ranking factors. 

That being said, mobile devices use unstable internet connections, and they typically have less computing power than desktop devices. You need to remember that if you’re using Responsive Web Design to serve the same website on all devices. Optimize your web performance with mobile devices in mind.

Mobile configuration: how to implement a mobile site?

The differences between the possible mobile configurations: Responsive Web Design, Dynamic Serving, and Separate URLs

There are three main approaches that you can take in configuring your website for mobile devices.

Responsive Web Design

Responsive Web Design is the easiest to implement, optimize and maintain, and is recommended by Google. If this is what you’re using, and it’s properly set up, there isn’t much optimization that you need to do. With this mobile configuration, the HTML code and URL remain the same as for the desktop page, and the content adapts to the screen size of the device

Dynamic serving

Dynamic serving serves specific HTML, CSS, and JavaScript to users across different devices. In essence, the server detects the user agent that is accessing the site and serves the appropriate assets. This solution is viable, but it requires you to maintain and audit several versions of your website.

Separate URLs

There is yet another configuration that, apart from using different codes, also uses separate mobile and desktop URLs for your site. Remember the ‘m.’ in URLs for mobile websites? That’s the one! Though it’s surely a less common solution these days than it was in the past, some websites still use it for differentiating between website versions for different devices.

Google provides additional details that should be considered if you’re using this mobile website approach:

  • Check your robots.txt file and whether it works for both sites. 
  • Pay special attention to your rel=canonical and rel=alternate link tags and how they are set up. 
  • Adjust the error pages so that they are the same on both sites. 
  • You should also verify both versions in Search Console and check if your mobile site has sufficient capacity that will let it handle potentially increased crawl rates. 

If you are looking for more information, check out this analysis of the three mobile configuration options compiled by Flowmatters

Responsive Web Design is the preferred configuration, but it doesn’t mean that Google would dismiss all the other types. However, sites that serve different code or URLs are much more prone to experiencing issues or errors and are more demanding when it comes to their maintenance. 

What does mobile-first indexing mean for SEO?

Mobile-first indexing update is a response to the ever-growing need for websites that are fast, accessible, render correctly and provide an outstanding experience for all users. The update has been gradual, unlike many other Google updates that brought on disruptive and sudden changes. In this case, Google recognized that getting prepared for it might be a process.

It’s vital to ensure that Google can access all the essential content that you want to be used for ranking your website. An integral aspect of preparing for mobile-first indexing is to be aware of how mobile searches contrast from desktop ones, with respect to how queries are formed, as well as the growing use of voice search. Scroll-depth and click-through rates also differ across mobile and desktop versions of pages, as mentioned above. 

With most of the world, including Google, going mobile-first, you should take action and make sure you are not left behind!