Mobile SEO Checklist for a Fast, Mobile-Friendly Site

Why mobile SEO matters

Google now crawls, indexes and ranks almost every website using its smartphone crawler. It started moving to mobile-first indexing in 2016 and announced in October 2023 that the move was complete [2]. In practice that means the mobile version of your site is the version Google judges. If a heading, a block of text, an image or a piece of structured data only exists on desktop, as far as Google is concerned it isn’t there [3].

Coalition Technologies, a design and marketing agency, set out mobile SEO as a four-stage flowchart in 2017: choose a mobile platform, make the pages crawlable, make them fast, then get the design and content right [1]. That order still works as a checklist, and the steps below follow it, updated for how Google works now.

1. Choose the right mobile setup

There are three ways to serve a site to phones, and Google’s documentation describes all three [3]:

Setup	URL	HTML	Verdict
Responsive design	Same for every device	Same, CSS adapts the layout	Recommended by Google
Dynamic serving	Same for every device	Different per device, chosen by the server	Works, but harder to get right
Separate mobile site (m-dot)	Different, such as m.example.com	Different	Avoid for new sites

Google says it “recommends Responsive Web Design because it’s the easiest design pattern to implement and maintain” [3]. Coalition’s checklist made the same recommendation, pointing out that one URL is easier to share and link to and that you only maintain one version of each page [1]. Dynamic serving needs the server to detect the device and send a Vary: User-Agent header, and separate mobile sites need canonical and alternate tags linking every desktop page to its mobile twin [3]. Both make it easy for the mobile version to fall behind the desktop one, which is exactly what mobile-first indexing punishes.

2. Make sure Google can crawl and index your mobile pages

• Don’t block resources. Google needs to load your CSS, JavaScript and images to see the page as a phone user does. Check robots.txt isn’t blocking them [1][3].
• Keep content the same on mobile and desktop. Same main text, headings, images (with alt text) and videos. Hiding content behind tabs or accordions is fine, but removing it on mobile is not [3].
• Keep structured data on the mobile version. Schema.org markup for products, reviews, articles, FAQs and so on must be on the mobile pages, with the right URLs [3].
• Use the same titles and meta descriptions on both versions [1][3].
• Don’t lazy-load main content in a way Google can’t trigger, such as only loading text when someone scrolls or clicks [3].
• If you run separate mobile URLs, use rel=”canonical” and rel=”alternate” between each pair, make sure error pages match, and include both in your sitemap setup [3].

The 2017 checklist suggested a separate mobile XML sitemap. That was mainly for old feature-phone pages; a normal sitemap is enough for a responsive site.

3. Make your pages fast on a phone

Page speed is now measured mainly with Google’s Core Web Vitals, which are based on real visitors’ experience in Chrome [4]. The targets for a good result are:

• Largest Contentful Paint (LCP) within 2.5 seconds, for loading speed.
• Interaction to Next Paint (INP) under 200 milliseconds, for how quickly the page responds to taps. INP replaced First Input Delay as a Core Web Vital in March 2024 [4].
• Cumulative Layout Shift (CLS) under 0.1, for how much the layout jumps around while loading.

The fixes on Coalition’s list are still the main ones: compress and resize images for mobile, turn on text compression, cut redirects, minify CSS, JavaScript and HTML, and improve your server response time [1]. Add modern image formats such as WebP or AVIF, lazy loading for images below the fold, and fewer third-party scripts, which are often the biggest cause of slow INP on small business sites.

One item has dated: the checklist suggested building pages in AMP. Google stopped requiring AMP for the mobile Top Stories carousel in 2021 [5], and a fast normal page now does the same job.

4. Design and write for small screens

• Avoid intrusive pop-ups. Google’s guidance warns against interstitials that cover the whole page or push people to a separate page before they can see content, unless the law requires it, such as an age check [6]. A small banner is fine.
• Use readable text. A base font size of 16 CSS pixels is the usual minimum for body text. The 2017 graphic said “16 pt”, which is larger; pixels is what browsers and Google’s tools use.
• Space out buttons and links so people can tap the right one. Lighthouse flags tap targets smaller than about 48 by 48 pixels.
• Set the viewport. Every responsive page needs a viewport meta tag so it scales to the screen.
• Use HTML5 video and animation. Flash, which the checklist warned against, no longer runs at all: Adobe ended support at the end of 2020 [7].
• Keep content original and useful. Mobile readers scan, so lead with the answer, use short paragraphs and clear headings, and don’t strip out content to make the page shorter [1][3].

How to test your site on mobile

Google retired its Mobile-Friendly Test and the Mobile Usability report on 1 December 2023 [8]. Use these instead:

• PageSpeed Insights for Core Web Vitals and a mobile Lighthouse audit of any URL.
• Search Console’s Core Web Vitals report to see which groups of pages are slow for real users [4].
• Search Console’s URL Inspection tool to see the page as Googlebot Smartphone renders it.
• Chrome DevTools device mode, and an actual phone on a 4G connection.

Questions about mobile SEO

What is mobile-first indexing?

Google uses the mobile version of your site, crawled with its smartphone crawler, for indexing and ranking. The switch was completed in October 2023 [2][3].

Should I use responsive design or a separate mobile site?

Responsive design. Google recommends it as the easiest pattern to implement and maintain, and it avoids the risk of the mobile version missing content [3].

Can I do SEO on a mobile phone?

You can do a lot of it. Search Console and PageSpeed Insights both work in a mobile browser, and most website builders and WordPress have mobile apps for editing pages, though detailed technical work is easier on a computer.

What are good Core Web Vitals scores?

LCP within 2.5 seconds, INP under 200 milliseconds and CLS under 0.1 [4].

Do I still need AMP for mobile SEO?

No. AMP has not been required for the Top Stories carousel since 2021 [5]. A fast, standard responsive page is enough.

Does Google still have a mobile-friendly test?

No. It was retired on 1 December 2023 [8]. Use Lighthouse in PageSpeed Insights or Chrome instead.

Sources

1. Coalition Technologies, Mobile SEO Infographic Checklist, 16 October 2017, the creator’s post for this infographic.
2. Google Search Central Blog, Mobile-first indexing has landed, 31 October 2023.
3. Google Search Central, Mobile site and mobile-first indexing best practices.
4. Google Search Central, Understanding Core Web Vitals and Google search results.
5. Google Search Central Blog, Timing for bringing page experience to Google Search, November 2020.
6. Google Search Central, Avoid intrusive interstitials and dialogs.
7. Adobe, Adobe Flash Player end of life.
8. Google Search Central Blog, A new mobile friendly testing tool (update of 1 December 2023 on its retirement).

Last reviewed 2 November 2026