Mobile Website Audit: Responsive and Indexing Checks

Why Mobile Audits Matter

A mobile website audit checks whether the same primary content, metadata, structured data and crawlable links are available to users and Google on the mobile render. Test real devices as well as emulation because viewport size alone cannot reproduce browser and input differences.

A mobile audit evaluates your site on the devices your users actually use, under the network conditions they actually experience. What looks and works great on a desktop with fibre broadband may be broken on a phone with a 4G connection.

Mobile-First Indexing

Since 2023, all websites are crawled and indexed using the mobile version. This means:

• Content must be identical: If content exists on desktop but is hidden, collapsed, or removed on mobile, Google may not see it at all.
• Structured data must be on mobile: Schema markup that only appears in the desktop version won't be used by Google.
• Internal links must work on mobile: Navigation that relies on hover states or desktop-only menus may prevent Google from discovering linked pages.
• Images must be present: Images hidden on mobile via CSS display:none may not be indexed. Use responsive images instead of hiding them.

Responsive Design Checks

• Viewport meta tag: Every page must include <meta name="viewport" content="width=device-width, initial-scale=1">. Without it, mobile browsers render the page at desktop width.
• No horizontal scrolling: Content should never overflow the viewport width. Check for fixed-width elements, wide tables, or oversized images that force horizontal scrolling.
• Readable text without zooming: Body text should be at least 16px. Users shouldn't need to pinch-zoom to read your content.
• Flexible layouts: Use layout methods and units that adapt to available space. Test boundary widths derived from the design, content and analytics, including narrow mobile and zoomed states.
• Images scale correctly: Images should have max-width: 100% and height: auto to prevent overflow. Use the picture element or srcset for different viewport sizes.
• Tables are readable: Data tables often break on mobile. Use responsive table patterns — horizontal scrolling wrappers, stacked layouts, or simplified mobile versions.

Mobile Speed Optimisation

Mobile speed is a distinct challenge from desktop speed. Mobile devices have slower CPUs, less RAM, and often use cellular connections with higher latency.

• Test on real mobile conditions: Throttle to 4G speeds (1.6Mbps down, 150ms RTT) when testing. Use Lighthouse's mobile emulation or WebPageTest with a mobile device profile.
• Reduce JavaScript payload: Mobile CPUs are 3-5x slower than desktop at parsing and executing JavaScript. Every KB of JS matters more on mobile.
• Optimise for high-latency connections: Each HTTP request adds 100-300ms of latency on mobile. Reduce the number of requests and use HTTP/2 multiplexing.
• Preconnect to critical origins: Use <link rel="preconnect"> for external domains that serve critical resources (fonts, APIs, CDNs).
• Target LCP within 2.5 seconds: Use 75th-percentile field data where available and trace representative mobile loads to find the responsible element and subparts.

Touch and Navigation

• Tap targets have sufficient size or spacing: WCAG 2.2 AA sets a 24 by 24 CSS pixel criterion with spacing and inline exceptions. Test larger controls where the audience or task needs them.
• Adequate spacing between tap targets: At least 8px of spacing between clickable elements to prevent accidental taps.
• No hover-dependent interactions: Dropdown menus, tooltips, and hover effects don't work on touch screens. Ensure all interactive elements are accessible via tap.
• Mobile menu is usable: Hamburger menus should be easy to open and close, menu items should be large enough to tap, and the menu shouldn't cover the entire viewport.
• Forms are mobile-friendly: Use appropriate input types (email, tel, number) to trigger the right mobile keyboard. Labels should be above fields, not beside them.
• Interstitials preserve access: Check pages against Google's intrusive-interstitial guidance. Keep legally required notices proportionate and verify that users can reach the main content.

Mobile Content Parity

With mobile-first indexing, your mobile site must have the same valuable content as your desktop site:

• Same primary content: Text, images, and videos on desktop should also be on mobile. Content hidden behind "Read more" toggles is generally fine — Google can access accordions and expandable sections.
• Same headings: H1-H6 heading structure should be identical on mobile and desktop.
• Same internal links: Mobile navigation must link to the same important pages as desktop navigation.
• Same structured data: Schema markup should be present on the mobile version of every page.
• Same alt text on images: If you serve different images on mobile, they still need descriptive alt text.

Testing Tools

• Google URL Inspection: Inspect Google's indexed and live-test render for a representative URL. Use the result with browser testing rather than as a full usability verdict.
• Responsive browser testing: Use current Chrome, Safari and Firefox with zoom, portrait and landscape checks. Google's Mobile-Friendly Test and Search Console Mobile Usability report are retired.
• Chrome DevTools Device Mode: Emulate any mobile device with responsive design mode. Toggle the device toolbar with Ctrl+Shift+M.
• BrowserStack or LambdaTest: Test on real devices remotely. Essential for catching issues that emulators miss — especially iOS-specific rendering bugs.
• PageSpeed Insights (mobile): Compare field data with its collection window and use the mobile lab run to diagnose a reproducible problem. Do not compare raw Lighthouse scores from different test conditions.

Mobile Audit Checklist

• Viewport meta tag present on all pages
• No horizontal scrolling at any viewport width
• Text readable at 16px+ without zooming
• Target size and spacing checked against WCAG 2.2 AA and the needs of touch users
• Mobile menu functional and easy to use
• No hover-dependent interactions
• Forms use correct input types
• No intrusive interstitials
• Content parity with desktop version
• Mobile LCP within 2.5 seconds at the 75th percentile
• Images responsive with srcset
• Third-party scripts deferred on mobile
• Structured data present on mobile version

Google's mobile-first indexing guidance explains content and metadata parity. W3C documents the WCAG 2.2 target-size criterion. Continue with the Core Web Vitals audit for field-data interpretation.