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Understanding Google's Mobile-First Indexing

Profile photo of Martyn McDermott.

By Martyn McDermott

10 min read

Mobile phone with Google logo on screen.

OK, so mobile-first indexing isn't "hot news" anymore.

But that doesn't mean it's any less misunderstood, though.

In fact, over five years on and there's still some confusion about what the term actually means. But we'll get to that in a minute.

Let's start with what it's not.

Mobile usability is not the same as mobile-first indexing.

John Mueller, Search Advocate (English Google Webmaster Central office-hours hangout, 2019).

But do they have anything in common, though? You know, besides both having mobile in the name.

Yep. Neglect either one and you could see a drop in traffic.

So what's changed and what do you need to know?

Mobile-first indexing - the story so far

Google has been talking about mobile-first indexing in one way or another since around 2017.

And for good reason too.

Research suggests that the percentage of global web traffic on mobile devices has spiked in the past decade.

But by how much, exactly?

Well, as of November 2022, over 60% of all web traffic came via mobile phones. To put that figure into context, this was just 10.88% in 2012.

Essentially, this is the reason mobile-first indexing exists; it's why Google is placing so much emphasis on mobile-friendly websites.

But don't take our word for it.

Since the majority of users now access Google Search with a mobile device, Google primarily crawls and indexes pages with the smartphone agent going forward.

Google Search Central

The good thing is, most websites have now been moved over to the mobile index.

But not all of them.

Right. So which sites have been moved over and who's been left behind?

Well, seeing as mobile-first indexing is the default for any new website published after July 1st 2019, chances are yours has been mobile-indexed.


But what do you do if your site's older and isn't indexed by default?

How to get your site mobile-first indexed

To get your site mobile-first indexed, start by ensuring it meets the following criteria:

  • It has a mobile-friendly design and layout - try using responsive web design or separate mobile URLs (we'll go into more detail about this in a bit).

  • The mobile version of the site has the same content as the desktop version - ensure there are no significant differences in the HTML code.

  • The site is configured with a viewport meta tag - also check that images and videos are optimised for mobile devices.

  • The site's free of blocking resources - code like JavaScript and CSS can prevent the Googlebot from crawling the site.

And that's it. If your site's older than four years and meets these criteria, you can then submit it to Google Search Console for mobile-first indexing. Simple as that.

So how does mobile-first indexing actually work?

Google will use the mobile variant of your website as the primary version when crawling and indexing your site. Basically, this means Google favours the mobile version as its key source of information when ranking your pages in the search results.

This is a big change from the previous method. Previously, Google would index both the mobile and desktop versions of websites but it would use desktop versions for ranking purposes.

Fast-forward to today and if you display something on the desktop version that isn't shown on mobile, Googlebot won't see it. Simply put: anything you want to be indexed has to be on the mobile site.

So how does it rank mobile sites?

Google scores and ranks websites based on a complex architecture of factors. That's why it's well worth familiarising yourself with their Core Web Vitals. Essentially, Google will be testing your mobile site pages and scoring them based on speed, usability and stability.

What does mobile-first indexing mean for my website?

If your website's slow-to-load or isn't mobile-friendly, you could see a significant drop in traffic.

To be clear, though, a website that isn't mobile optimised and can be viewed on a mobile - albeit painfully - is still eligible for indexing.

That's because mobile friendliness and mobile responsive pages are not mandatory for mobile-first indexing.

Oh, so is it even worth worrying about?

In short: yes.

At the end of the day, Google prioritises pages that offer great user experiences. So if you're buried ten pages deep in the search results pages, is there any point in taking the chance?

Mobile-friendliness doesn't just benefit the end user, though; it's got a ton of upsides for businesses as well.

The benefits of Google's mobile-first indexing for website owners.

There are countless reasons to go mobile-first this year. Here are just some of the biggest benefits:

  • Focusing on page speed and mobile usability will result in better user experience (UX) and, quite possibly, higher conversion rates.

  • Mobile-first indexing helps Google learn how people are using their phones to search. In turn, this will help inform improvements in the overall quality of search results.

  • As mobile-friendliness is one of Google's priorities, sites that are mobile-optimised will likely see a ranking boost when indexed.

All in all, it's a win-win for everyone.

Well, except for anyone who still prioritises desktops.

What happens if my site isn't optimised for mobile?

Simple: if your website isn't optimised for mobile, you could see a decrease in traffic from Google (due to a lower ranking in search results).

But that's not all.

You might also start to see an increase in your bounce rates; a Google study revealed that up to 61% of users are unlikely to return to a website that isn't mobile-friendly.

Worse still, your website might load slower on mobile. And there's evidence to suggest users won't hang around for long if it does. Research shows that over half (53%) of mobile site visitors leave a page that takes longer than three seconds to load (Google).

Don't worry, it doesn't need to come to that. In fact, there's plenty you can do to satisfy Google's crawlers and your users.

How can I improve performance in Google's mobile-first index?

Here are four ways to ensure your site's performing well on all devices.

1. Test your website

First and foremost, take a look at your website on a mobile device.

Then ask yourself: does this feel easy to navigate and use?

If not, it's time to make some changes. Try Google's Mobile-Friendly Test tool to see how it stacks up.

2. Create mobile-friendly content

Once you've made sure your website is mobile-friendly, you'll need to ensure your content's working for phones too. This means creating content that's easy to read on a small screen.

Mobile users are often looking for quick answers to their questions, so it's important to make sure your content is clear and concise.

Not sure where to start? No problem. Our team of experts can help you create mobile-friendly content that appeals to end-users and search engines. Just get in touch for a chat.

3. Separate your sites

You could also try creating separate websites (and often separate domains) for mobile and web, e.g. and or Doing so can offer a variety of benefits:

  • Improved user experience - a separate mobile site can be optimised for smaller screens and touch-based navigation. And this makes it easier for users to navigate and find the information they need.

  • Increased speed - each site can be designed to load faster, improving the user experience and reducing bounce rates.

  • Better search engine optimisation - separate sites are also easier to optimise for mobile search engines. This will help improve visibility and drive more traffic to the site.

  • Greater flexibility - an individual mobile website can be designed and developed independently of the main website; this allows for greater flexibility and faster iterations.

  • Better analytics - finally, it's much easier to track and analyse mobile-specific metrics, e.g. bounce rates, click-through rates, and conversion rates.

4. Go responsive and 'feature-lite'

You can also develop a responsive website for mobile from the offset. This involves using CSS media queries and a flexible grid-based layout to adjust the design of the website; this is based on the screen size and resolution of the device that's accessing it.

Not only that, you could go 'feature-lite'. This involves presenting the optimal experience to a user; often an altered feature set due to browser-size limitations. For example, this is often used with SaaS platforms where you get a feature-lite version on mobile.

So those are some topline ideas. Now for some techie bits.

Technical stuff to remember about mobile-first

So mobile-first is designed to make things easier for everyone experiencing your site - whether that's humans or spiders. However, there are a few hard and fast rules to ensuring you get things right:

  • When having multiple versions of a site. It's essential that valuable content is shown on all versions. What's more, make sure you use the same URLs for both mobile and desktop versions

  • Allow Googlebot to access and render your site content. To do so, it's recommended you use the same meta robot tags on the mobile site. Importantly, remember that Google can't load content that requires user interactions to trigger it. So try not to lazy-load your primary content.

  • Ensure structured data is the same on all site versions. This applies if you have different mobile and desktop versions of your site. But if your site's responsive, this shouldn't be a problem.

  • Use testing tools, e.g. Google's Mobile-Friendly Test. This will help identify and address speed-related issues with your site. Page speed is an important ranking factor with the mobile-first index, so try and keep it front-of-mind.

  • Keep an eye on your Search Console. This will help you identify and fix mobile errors quickly. Get into a habit of regularly checking the 'mobile usability' and 'core web vitals' reports in Search Console to keep you in the loop of what's going on behind the scenes.

For more info, check out Google's mobile-first indexing best practices.

The final word on mobile first indexing (for now)

Overall, we reckon mobile-first indexing is a step in the right direction for search. But beyond the way Google indexes pages, it's tailor-made to improve the experience for both users and website owners.

And, these days, there's just no getting away from it.

Google's focus in this area is only set to grow as more and more people continue to use mobile as their primary devices.

So why wait any longer?

Start prioritising mobile today and see the benefits for years to come. Just follow our best practices and keep an eye on your website's analytics to ensure everything's performing as expected. You got this.

Mobile experience still not performing well? Don't worry, we'll get your site up to speed.

Just get in touch for a chat.

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