Introduction
Google officially moved to mobile-first indexing for all websites in 2024, meaning the mobile version of your site is the primary version used for indexing and ranking. If your mobile experience lags behind desktop, your rankings will suffer.
Responsive Design
Use a single responsive URL structure rather than separate m.domain.com subdomains. Responsive design ensures the same HTML is served to all devices, eliminating the risk of inconsistent content between desktop and mobile versions.
Mobile Page Speed
Mobile users are often on slower connections. Aim for a Largest Contentful Paint (LCP) under 2.5 seconds on 4G. Compress images, use next-gen formats (WebP/AVIF), defer non-critical JavaScript, and leverage browser caching.
Tap Targets & Readability
Ensure all buttons and links have a minimum tap target size of 48×48 CSS pixels. Use a base font size of at least 16px to ensure readability without zooming.
Avoid Intrusive Interstitials
Google penalises pages that show large pop-ups or interstitials on mobile before users can see the main content. Cookie banners and age-verification gates may be exempt, but marketing pop-ups are not.
Structured Data on Mobile
Ensure all structured data present on desktop is also present on the mobile version. Google only reads the mobile version during indexing, so desktop-only schema markup is invisible to it.
Conclusion
Mobile-first SEO is not a separate discipline — it is simply the baseline expectation for 2025. Design for mobile first, then enhance for desktop.