Mobile-first indexing means Google uses the mobile version of your pages, fetched by its smartphone crawler, to index and rank them. If your phone page shows less than your desktop page, Google sees the smaller version. Responsive design, where one page serves every screen, avoids nearly all the risk.
What is mobile-first indexing?
Google's documentation defines it as using the mobile version of a site's content, crawled with the smartphone agent, for indexing and ranking. A mobile version is not required for a page to appear in Search, but Google strongly recommends one.
The practical meaning is simple. The page a visitor sees on a phone is the page Google reads. Anything that exists only on desktop may as well not exist.
Is mobile-first indexing the same as mobile-friendly?
No, and people mix them up. Mobile-friendly describes how pleasant a page is to use on a phone: readable text, tappable buttons. Mobile-first indexing describes which version of the page Google reads. A page can be clumsy on a phone and still be indexed from its mobile version. It can also look fine to a visitor but hide content from Google if that content only loads on desktop.
Which site setup is safest?
Google describes three configurations.
| Setup | How it works | Risk |
|---|---|---|
| Responsive design | One URL, one HTML file, layout adapts to the screen | Lowest. Content and metadata are already the same |
| Dynamic serving | One URL, different HTML per device | Medium. The mobile HTML must match the desktop content |
| Separate URLs | A different address for mobile, often an m-dot subdomain | Highest. Many things must match on both sites |
Google calls responsive design the easiest to implement and maintain, and says its extra guidance applies to the other two setups. If you build on a modern site builder or framework, you are most likely already responsive.
What should you check on your site?
Use this list on one important page, then on a few templates. Items come from Google's mobile-first guidance linked above.
- Same primary content. The phone page should carry the same main text and clear headings as desktop. Google notes that having less content on mobile can lower traffic. Tabs and accordions are fine for layout.
- Same robots directives. Use matching
noindexandnofollowmeta tags on both versions. A stray tag on one version can drop the page. Our posts on the noindex tag and robots.txt versus noindex explain the difference. - Nothing blocked in robots.txt. Do not block the scripts, styles or images the phone version needs.
- No content hidden behind interaction. Google advises against lazy-loading primary content so that it only appears after a swipe, click or typing.
- Same structured data. Keep schema markup equal on both versions. If you use separate URLs, the mobile addresses go in the markup.
- Same titles and descriptions. Your title tag and meta description should be equivalent on both.
- Same images and alt text. Use the same image addresses and alt text, so image traffic does not dip.
Extra checks for separate mobile URLs
If you run an m-dot site, Google lists more requirements. The most commonly missed:
- Error status codes must match. If the desktop page returns an error, so should the mobile one.
- Mobile pages should use a canonical tag pointing to the desktop page, and desktop pages should point to the mobile one with an alternate link. See our guide to the canonical URL.
- Do not redirect many desktop pages to a single mobile homepage.
- Verify both versions in Search Console, and make sure the mobile server can handle a higher crawl rate.
If this list feels like a lot, that is the argument for moving to a responsive design.
How do you see what Google sees?
Use the URL Inspection tool in Search Console on a page and look at the HTML Google fetched. Compare it with what you see on your phone. If a section, heading or link is missing from what Google fetched, work out why before changing anything else. Our explainer on crawling and indexing covers how the two stages differ, and the guide to checking indexing shows the tool step by step.
Speed matters too, because most mobile visitors are on slower connections. See Core Web Vitals.
Frequently Asked Questions
Do I need a separate mobile site?
No. Google recommends responsive design, where one page adapts to each screen. A separate mobile site is allowed but adds many things that must stay matched.
Will desktop-only content hurt my rankings?
It can. Google reads the mobile version, so content that appears only on desktop may not be indexed. Move important text and links into the phone page.
Are tabs and accordions bad on mobile?
No. Google's guidance says they are acceptable for layout. The warning is about primary content that loads only after a user action.
Does a site with no mobile version still get indexed?
Yes. Google says a mobile version is not required to appear in Search. You will just be indexed from what Google can fetch, and phone visitors will have a poor experience.
How do I know my site is on mobile-first indexing?
Google's documentation does not give a single switch to check. The practical test is to inspect a few key pages in Search Console and confirm the fetched HTML matches what a phone shows.