Mobile-First Indexing Explained

Mobile-first indexing means Google uses the mobile version of a page, crawled with its smartphone crawler, for indexing and ranking. If something exists on your desktop page but not on the mobile version, Google may never see it. For most sites built with responsive design, this already works; the risk is for sites where the mobile page shows less than the desktop one.

What it means in plain terms

Google’s crawler visits your pages pretending to be a smartphone. Whatever that mobile view contains, including text, headings, links, images, structured data and metadata, is what Google uses to understand and rank the page. The desktop view is no longer the main source.

This is not the same as being “mobile friendly”. Mobile-friendly describes how pleasant a page is to use on a phone. Mobile-first indexing describes which version of the page Google reads. You can have one without the other, but a page that is hard to use on a phone is a poor result either way.

What to keep the same on mobile and desktop

Google’s guidance for mobile sites covers most of this, and the rest is common sense. Keep these the same between versions:

• Content. The same main text and the same meaningful headings.
• Structured data. The same markup on both. If you have to prioritize, Google suggests starting with Breadcrumb, Product and VideoObject.
• Metadata. The same titles, meta descriptions and robots meta tags.
• Images and video. The same image and video content, with alt text, and the same video structured data.
• Links. The same important links, so crawlers can find the same pages.

If your mobile page cuts content to save space, that cut content is what Google indexes.

Three ways to build a mobile site

Setup	How it works	Mobile-first risk
Responsive design	One URL and one HTML, with CSS adapting the layout	Lowest. Content and metadata are the same by design.
Dynamic serving	One URL, but different HTML for mobile and desktop	Medium. Easy for the mobile HTML to differ from the desktop HTML.
Separate mobile URLs	A separate mobile site, often on m.	Highest. Two sites to keep in step, plus extra annotation work.

Google notes that its best-practice list for matching content applies to dynamic serving and separate URLs, since with responsive design the content and metadata are the same by default. Responsive design is the simplest to maintain.

Common mobile-first problems

• Content missing on mobile. A shortened mobile page, or text removed to save space.
• Structured data on desktop only. Markup that appears only in the desktop HTML.
• Different titles and descriptions on the mobile version.
• Blocked resources. CSS, JavaScript or images blocked from crawlers, so the mobile page cannot render properly.
• Lazy-loaded content that never loads for the crawler, such as content that needs a scroll or click that does not happen.
• Mobile pages that error out, or serve a different, thinner page to phones.
• Pages that are unusable on mobile, such as a wide layout that needs sideways scrolling, tiny text, or buttons too close together.

How to check your site

1. Look at the page on a phone-sized screen. Run it through the Mobile Friendly Test to check the viewport tag, sideways scrolling, text size, tap targets and zoom. See How to Check If Your Website Is Mobile Friendly for the full process.
2. See what Google sees. In Google Search Console, use the URL Inspection tool on an important page, then look at the crawled or live-tested version. Check that the content, links and structured data you expect are there.
3. Compare versions. If your site serves different HTML to phones, compare the two. In Chrome, open developer tools, turn on the device toolbar, reload the page, and compare what appears.
4. Crawl your site. The Page Audit Checker lists titles, descriptions, headings, links and structured data for each page, which helps you spot templates with missing data.
5. Check your robots.txt to make sure you are not blocking files the page needs to render.

A mobile-first checklist

• The site uses responsive design, or the mobile version matches the desktop version.
• The viewport meta tag is present.
• Main content, headings and links match on both versions.
• Structured data matches on both versions.
• Titles and meta descriptions match on both versions.
• Images have alt text and load on mobile.
• CSS, JavaScript and images are not blocked from crawlers.
• Text is readable and buttons are easy to tap without zooming.
• Pages load quickly on a phone.

Mobile-first checks are one part of a wider review. See the Technical SEO Audit Checklist for the rest.

Frequently asked questions

Is mobile-first indexing the same as mobile-friendly?

No. Mobile-first indexing is about which version Google reads for indexing and ranking. Mobile-friendly is about how easy a page is to use on a phone.

Do I need a separate mobile site?

No. Responsive design, where one page adapts to every screen, is the simplest approach and carries the least risk.

Does mobile-first indexing mean desktop pages are ignored?

Google uses the mobile version for indexing and ranking, so that is the version that counts. A desktop page can still exist, but anything only on the desktop version may not be seen.

How do I know if my site is on mobile-first indexing?

In Search Console, the URL Inspection tool shows which Googlebot crawled the page. Most sites are now crawled with the smartphone crawler.

Does mobile-first indexing affect page speed?

Speed is a separate topic, but a slow mobile page is a poor experience, and Google measures how pages perform for real users on their devices. Compress images and keep scripts light. A tool such as the Image to AVIF Converter can help reduce image weight.