Google finished moving to mobile-first indexing some time ago. In plain terms: when Google decides what your page is about and where it should rank, it reads the version a phone would load, not the desktop one. If the two differ, the mobile version wins, for better or worse.
For most sites built in the last few years this changes nothing, because the mobile version is the same page reflowed. For older sites, sites with a separate mobile template, or sites where the builder hides sections on small screens, it quietly explains a lot of lost rankings. Here is what to check.
What Google actually looks at
The smartphone crawler fetches your page and renders it. What it can see there is what counts: the text, headings, images, links, structured data and speed of the mobile render. Content that exists only on desktop, or that is collapsed away with “display: none” on mobile, is discounted or missed entirely.
The five checks that matter
1. Same content on both
Open your key pages on a phone and on a laptop and compare. Every heading, paragraph, FAQ and internal link that appears on desktop should appear on mobile. Page builders often ship a “hide on mobile” toggle that designers use to tidy layouts; each use of it removes content from your ranking version.
2. Speed on a mid-range phone over mobile data
Google’s Core Web Vitals are measured from real Chrome users, most of them on phones. The usual culprits are uncompressed images, video autoplaying above the fold, and a page builder loading every script on every page. Our free site audit runs the same PageSpeed checks Google uses, mobile and desktop.
3. Usable with a thumb
Tap targets that are too small or too close, text that needs pinching to read, menus that need precision. These show up in Search Console as usability issues and, more importantly, as visitors who leave.
4. Structured data and metadata present on mobile
If your FAQ schema, LocalBusiness schema or canonical tag is added by a desktop-only template, the mobile version lacks it and Google does not see it. Check the mobile source, not only the desktop one.
5. One URL, not two
Separate m-dot sites (m.example.com) are a maintenance burden and a ranking risk. If you still run one, plan the move to a single responsive site; Google’s own guidance has pointed that way for years.
Common mistakes we still find
- Hero image at 4 MB, served at full size to phones.
- Service descriptions hidden behind “read more” accordions that never render their content.
- A mobile menu that lists half the pages the desktop menu does, so half the site is one link deeper for the crawler.
- Pop-ups that cover the content on load. Google treats intrusive interstitials as a negative signal on mobile.
- Fonts and icons loaded from three different providers, each adding a round trip.
What to do this week
- Run Search Console’s page experience and mobile reports and fix anything red.
- Compare mobile and desktop content on your ten most important pages; restore anything hidden.
- Compress and resize images; lazy-load everything below the first screen.
- Test the site on an ordinary Android phone on 4G, not on an office Wi-Fi with a flagship.
If the site was built more than a few years ago, or on a heavy builder, the cheapest fix is often a rebuild on a lighter stack. Our web design work starts from mobile performance for that reason, and our piece on responsive design covers the technical side.
Is mobile-first indexing the same as mobile-friendly?
No. Mobile-friendly describes how a page behaves on a phone. Mobile-first indexing means Google uses the mobile version of the page as the basis for ranking. A page can be mobile-friendly and still hide content that only the desktop version shows.
Does my desktop site still matter?
For visitors, yes. For ranking, only the parts that also exist on mobile count. Keep the content identical and let the layout adapt.
How do I check what Google sees on mobile?
Use the URL inspection tool in Search Console and view the tested page and screenshot. It shows the rendered mobile version Google used.
Do accordions and tabs hurt mobile SEO?
Not if the content is in the HTML and only visually collapsed. They hurt when the content is loaded only after a tap, because the crawler never taps.
What is a good mobile speed score?
Aim for the Core Web Vitals thresholds: largest content painted within 2.5 seconds, interaction delay under 200 milliseconds, minimal layout shift. The PageSpeed score is a guide; the field data is what Google uses.