Mobile-First Indexing in Plain English

For many years, search engines judged a website by how it looked and read on a desktop computer. That changed as more people searched on phones. Today, the version of your site that a smartphone sees is the version that search engines use to decide what your pages contain and how to rank them.

This is called mobile-first indexing. It sounds technical, but the idea is simple, and for most small businesses with a modern website it needs little more than a quick check. This article explains what it means, what can go wrong and how to be sure your site is fine.

What it means

Google's documentation explains that it uses the mobile version of a site's content, crawled with a smartphone crawler, for indexing and ranking. The desktop version is not the main reference. If your mobile pages contain less than your desktop pages, then, as far as indexing is concerned, your pages contain less.

Google's description of how search works says that indexing involves analysing the text, images and video on a page and storing the information in a large database. With mobile-first indexing, the page analysed is the one a phone would receive.

For most visitors this is already the reality. Many of your customers will first see your site on a phone, and a version that works well there matters on its own account.

Why it can go wrong

For sites built with a single responsive design, where the same page adapts to the screen, there is usually no problem: the content is the same, and only the layout changes. Trouble arises when the mobile version is different.

Content hidden or removed on mobile. To save space, some designs drop sections, shorten text or remove images on small screens. If the removed content mattered for search, it is no longer counted.

A separate mobile site. Some older sites serve a different, stripped-down version to phones at a different address. These often have less content, different titles and missing markup.

Content that loads only on interaction. Text that appears only after a tap, or that is loaded by a script after the page has settled, may not be seen reliably.

Blocked resources. If the robots file stops crawlers from fetching the scripts or styles needed to render the mobile page, it may appear broken.

Different metadata. Titles and descriptions that differ between versions confuse matters.

What should match

Google lists the main things that should be equivalent between the mobile and desktop versions.

Content

The primary content should be substantially the same. Layout and design can differ, but the information should not. If a paragraph, a table or a list is important, it should appear on mobile too.

Titles and descriptions

The title and meta description should match across versions, so that search results show the same information.

Structured data

If you use structured data, include the same markup on mobile pages as on desktop, matching the visible content. Google highlights breadcrumb, product and video types in particular.

Images and video

Use the same images and videos on both, with the same quality, formats, addresses and alternative text and captions. Make sure that images are not lazy-loaded in ways that prevent them from being seen.

Links

Key links, including internal links that help crawlers navigate, should be present on mobile. If your mobile menu hides links that appear on desktop, check that crawlers can still reach those pages.

Access

Make sure that crawlers are not blocked from the resources they need to render the page. Do not use different robots rules for mobile.

What it does not mean

Mobile-first indexing is about which version is used for indexing. It does not mean that desktop is ignored by visitors or that you need a separate mobile site. It does not mean mobile pages get a ranking boost. It does not require an app. And it does not mean your desktop design must be dull.

A single responsive site is the simplest approach, and the one that avoids most problems.

Check your site in ten minutes

You can test this without special skills.

1. Open your site on a phone, and also on a computer. Compare the main pages side by side.
2. Look for missing content. Does any text, image, table or section appear on desktop but not on the phone?
3. Check the menu. Can you reach every important page from the phone menu?
4. Compare titles. The text in the browser tab or when sharing the page should match.
5. Open Search Console, if you have it, and use the inspection tool on a key page. It shows how Google last crawled the page, and the rendered version it saw.
6. Check the page experience report, which reports on loading, responsiveness and stability. Google's guidance defines targets of 2.5 seconds for the main content, 200 milliseconds for responsiveness and a layout shift score of 0.1 or less.
7. Test on a real phone, on mobile data, not just by shrinking your browser window.

If you spot differences, ask whoever built the site to fix them, or adjust the settings in your platform.

Fix the common problems

Hidden text on small screens. Show it, perhaps in a collapsible section that is present in the page's content. Content that is collapsed for design reasons but present in the page is normally fine; content that is removed is not.

A separate mobile site. Consider moving to a responsive design. If you must keep separate versions, ensure they have equivalent content, matching metadata and proper links between them.

Lazy-loaded content that never appears. Ensure that content loads when it enters the screen without requiring a tap or a scroll that a crawler would not perform.

Different titles and descriptions. Use the same template on both.

Missing structured data. Add it to the mobile version, or better, use a single version.

Blocked resources. Check the robots file and the settings of your site for rules that block scripts and styles.

Design for phones, not just for crawlers

Passing the indexing check is a minimum. The real goal is a site that is good to use on a phone.

• Readable text without zooming.
• Tap targets large enough and far enough apart.
• Simple, fast pages.
• Forms that work with a phone keyboard.
• A clear phone number and address, tappable.
• Contrast and accessibility suitable for outdoor, one-handed use.
• No intrusive pop-ups covering the content.

A site that people find pleasant on a phone is also likely to satisfy the engines that serve them. Google's guidance on helpful content emphasises that content should be created primarily for people, and visitors on phones are people with limited screens and patience.

Keep checking

Mobile-first checks are not once-off. After any site redesign, platform change, new plug-in or template update, repeat the checks. Add them to your launch checklist and your quarterly site review.

A worked example

A small dental practice has a handsome desktop site with a long page of treatments, each with a detailed description and a price guide link. On phones, the design shows only the treatment names, hiding the descriptions behind a "more" tap that is built to load text only on request.

The owner uses the inspection tool in Search Console on the treatments page and sees that the rendered version includes only the names. She realises that the detailed text is effectively missing for indexing. She asks her web designer to include the descriptions in the page, collapsed by default but present in the content. She also finds that the mobile menu omits a link to the emergency page, which she adds.

After the changes, the inspection shows the full text. Over the following weeks, the treatments pages begin to appear for searches that mention specific treatments, and mobile visitors spend longer on them.

Common mistakes

1. Assuming desktop is what counts.
2. Hiding or removing content on small screens.
3. A separate, thinner mobile site.
4. Different titles and markup.
5. Blocking resources.
6. Testing only by resizing a desktop browser.
7. Not rechecking after changes.

A checklist

• One responsive site
• Main content equal on phone and desktop
• Titles and descriptions the same
• Structured data matching
• Images and links consistent
• Resources not blocked
• Inspected in Search Console
• Good on a real phone
• Rechecked after changes

The search page here works on small screens, the categories page shows a simple hierarchy and the submit page lets a business add a listing that works on any device.

Mobile-first and your listings

Directories and listing sites are also read on phones, and the habits that make your own site work well apply to your profiles. Keep descriptions short enough to read without scrolling, put the phone number and address in plain text that can be tapped and use photographs that look good small. If a directory lets you add a link to your website, check that the destination page works on a phone and answers the question a mobile visitor is most likely to have, such as where you are or how to book. A visitor who arrives from a listing on a phone and finds a page that does not fit the screen is unlikely to stay.

Staying current

Standards for mobile pages continue to evolve, and so do the tools that report on them. Once a year, reread the guidance from the search engines you care about, run the checks again and ask whether your site still behaves as you intend. Look at your analytics to see how much of your traffic comes from phones, which pages they use and where they leave. Treat the numbers as a prompt to look at real pages on a real phone. The aim is simple: whatever device a customer picks up, your business should be easy to find and easy to use.

Frequently asked questions

Is my site affected if I only get desktop visitors? Indexing still uses the mobile version, whatever your visitors use.

Do I need an app? No. A good mobile website is enough for search.

What if my theme is old? Consider updating to a responsive one, or ask your developer to check how it behaves on phones.