How it came about
Google announced mobile-first indexing in 2016, as most searches had moved to phones, and gradually switched sites over. Today it applies to practically every website. There is no separate mobile index: it is one index, built from mobile pages.
What it means for your site
- Use responsive design, so mobile and desktop visitors get the same content.
- Don’t hide important text, images, links or structured data on mobile.
- Use the same titles, meta descriptions and headings on both versions.
- Make sure Googlebot can load your images, CSS and JavaScript.
- Keep the mobile page fast and easy to use.
A site without a mobile-friendly version can still be indexed, but it gives most searchers a poor experience and tends to perform worse.
Mobile-first indexing example
A company’s desktop site has a full guide with tables and expandable sections. Its mobile version hides the tables and cuts the text in half to save space. Because Google indexes the mobile version, the page is judged on the shorter text and the missing tables, and it loses rankings for terms that only the desktop version covered. The fix is a responsive design that shows the same content on both.
Mobile-first checklist
- Use responsive design with the same content on mobile and desktop.
- Check that mobile pages have the same titles, headings, structured data and links.
- Make sure images have alt text and are not blocked.
- Do not block CSS or scripts in robots.txt.
- Test pages with the URL Inspection tool and see the rendered mobile page.
- If you still have a separate m. site, check that content and canonical and alternate tags match.
Mobile-first mistakes
- Hiding content on mobile that you want to rank.
- Lazy-loading content that only loads on a user action Googlebot does not perform.
- Assuming that a desktop-only page will rank well.
Mobile-first FAQs
Is there a separate mobile index?
No. There is one index, built mainly from mobile pages. See responsive web design and crawlers.
Does it affect desktop rankings?
Yes, because the mobile version is the basis for both. See mobile page optimization and page speed.