How to check mobile friendliness of a website?

More than half of all web traffic now comes from mobile devices, with mobile accounting for 51.48% of global visits in Q2 2026 after peaking at 62.73% in 2025. This shift means Google evaluates and ranks websites primarily based on their mobile version through mobile-first indexing. For small business owners, a site that looks polished on desktop can still lose visibility and leads if it fails to perform well on phones.

Google’s mobile-first indexing uses the smartphone agent to crawl and index content, making mobile optimization essential for SEO success. As Google states, “Google uses the mobile version of a site's content, crawled with the smartphone agent, for indexing and ranking.” This approach has been the default for years, leaving no room for sites that prioritize desktop experience alone. Responsive design remains Google’s recommended pattern because it’s the easiest to implement and maintain while delivering consistent content across devices.

Before launch, AI Business Sites validates mobile friendliness using a three-tool protocol aligned with Google’s current recommendations. PageSpeed Insights diagnoses mobile usability and Core Web Vitals, the Rich Results Test verifies how Google’s mobile bot renders the page, and Lighthouse provides a comprehensive audit of performance, accessibility, SEO, and best practices. This process ensures the 85+ pages delivered in the $1,497 custom build meet mobile-first requirements from day one, supporting lead capture that works immediately on any device.

When Google retired its Mobile-Friendly Test on December 1, 2023, website owners lost a one-click answer to "is my site mobile-ready?" The good news: Google's own experts recommend a replacement workflow that's actually more thorough — it just takes three tools instead of one.

A Google Diamond Product Expert summed up the new approach plainly: use PageSpeed Insights to diagnose mobile usability, and the Rich Results Test to diagnose rendering. Lighthouse rounds out the trio as the comprehensive auditing engine behind both.

1. PageSpeed Insights — your mobile usability diagnosis

Paste your URL into PageSpeed Insights and it runs Lighthouse against a simulated mobile device, scoring performance and flagging mobile-specific failures like tap targets that are too small, illegible font sizes, and missing viewport configuration. It also reports Core Web Vitals from real user data. Since mobile devices account for over half of global web traffic — 51.48% as of Q2 2026 — this mobile report is the one that matters most.

2. Rich Results Test — rendering verification

Here's what Lighthouse can't do: show you the page exactly as Google's smartphone bot renders it. The Rich Results Test retains the "View Tested Page" functionality the old test was known for, letting you confirm that Google actually sees your content, images, and structured data on mobile — not a broken or empty version of the page. It's the closest thing to looking over Google's shoulder.

3. Lighthouse — the comprehensive audit

Lighthouse is an open-source, automated tool that audits four categories at once:

• Performance — Core Web Vitals like Largest Contentful Paint and layout shift
• Accessibility — contrast, tap target sizing, and screen-reader readiness
• SEO — crawlability, meta tags, and indexing blockers
• Best Practices — security, deprecated APIs, and console errors

Run it in about 30–60 seconds via Chrome DevTools (the Lighthouse panel), the command line, or a Node module. Each failed audit links to documentation explaining why it matters and how to fix it, so you're never left guessing.

At AI Business Sites, this three-tool sequence is standard before any client site goes live — the same discipline that matters for any custom build, because Google indexes and ranks the mobile version of your site first. A page that looks perfect on desktop but fails on a phone simply won't compete. Run all three tools on your key pages before launch, and you'll know exactly where you stand.

Before launching any site in our $1,497 custom build, we run a strict pre-launch mobile checklist aligned with Google’s mobile-first indexing requirements. This ensures equivalent content, headings, and meta tags on mobile and desktop, identical structured data (prioritizing Breadcrumb, Product, and VideoObject schema), and no lazy-loading of primary content on user interaction. We verify that no critical resources are blocked by robots.txt, all images include proper alt text and are high-quality, video uses supported formats and tags, and ads comply with the Better Ads Standard. Both mobile and desktop versions are confirmed in Search Console to avoid indexing discrepancies.

For performance, we enforce Core Web Vitals thresholds: LCP under 2.5 seconds, INP below 200 milliseconds, and CLS under 0.1 on mobile. These targets are critical given that mobile traffic has consistently exceeded 50% of global web traffic since 2017, reaching 51.48% in Q2 2026, with regional shares as high as 75% in Africa and 73% in Asia-Pacific. Manual checks on real device viewports (375px, 390px, 412px, 430px widths) validate touch target sizing (minimum 48×48px), font legibility (16px base size), and absence of horizontal scrolling. This comprehensive approach supports the 85+ pages launched in 7 days and the 14+ new SEO pieces published monthly, ensuring they perform well in high-mobile verticals like local services and e-commerce.

Knowing how to test is one thing; running those tests before launch is another. Here's how our build process applies the protocol above — the same three-tool workflow Google's own community experts recommend — before a single page goes live.

Every site we build starts mobile-first. The $1,497 custom build produces 85+ pages on React/Next.js, and each one is validated against the same protocol you just learned: PageSpeed Insights for mobile usability diagnosis, the Rich Results Test for rendering verification, and Lighthouse for the comprehensive audit. This mirrors the workflow Google's Diamond Product Experts recommend following the retirement of the dedicated Mobile-Friendly Test in December 2023.

Beyond the tools, every page is checked against Google's mobile-first indexing checklist — the same requirements Google uses to crawl and rank your site with its smartphone agent. That means verifying:

• Equivalent content, headings, and meta tags on mobile and desktop
• The same structured data on both versions, with no missing schema
• No lazy-loaded primary content or robots.txt-blocked resources
• Proper image alt text and high-quality images on mobile

Why the rigor? Mobile devices have generated more than half of global web traffic since 2017, peaking at 62.73% in Q2 2025. For local service businesses — the trades, clinics, and contractors we build for — a page that fails on mobile is a page that loses the customer standing in their driveway searching on a phone.

The testing doesn't stop at launch, either. Under managed support, the content engine publishes 14+ new pages every month, and every new page runs through the same validation before it ships. Lighthouse's audit framework is built for exactly this — as Google's documentation puts it, failed audits serve as indicators for improvement, each with a reference explaining why it matters and how to fix it.

That's the real difference between a one-time check and a system: mobile friendliness isn't a box you tick once. It's a standard that has to hold as your site grows. We treat it as part of the build, not an afterthought — so when Google's smartphone crawler reaches your pages, there's nothing to penalize.

If you'd like to see what this looks like for your business, book a free strategy call. Thirty minutes, no obligation — just a real conversation about your site, your goals, and whether a mobile-first build makes sense for you.