Mobile-First Indexing: Best Practices + Tips for Ecommerce

If you run an online store, your customers are almost certainly browsing, researching, and buying on their smartphones. Mobile traffic now dominates global browsing habits, with more than 64% of global web traffic coming from mobile devices as of July 2025.

In response, Google has shifted to mobile-first indexing, primarily evaluating your website through a smartphone Googlebot. That means your search rankings now depend on the mobile version of your website, making mobile SEO essential for visibility and revenue. If your mobile pages load slowly, hide important content, or create friction for shoppers, your rankings will drop.

Understanding how Google evaluates your site—and optimizing accordingly—can directly impact your store’s visibility and sales. In this guide, you’ll learn what mobile-first indexing means, why it matters for ecommerce, and how to optimize your mobile and desktop site so both Google and your customers get the best experience.

What is mobile-first indexing?

Mobile-first indexing is Google’s system for crawling and evaluating web pages with a smartphone user agent instead of a desktop crawler. In practice, this means Google looks at your mobile version to determine:

• What content gets indexed. This is what Google stores in its searchable database and can show in search results.

• Your site’s performance score. Your score is calculated according to Google’s Core Web Vitals.

• How users interact with your mobile site. Are they exploring multiple pages or bouncing as soon as they land on your site?

• Your overall search engine rankings. This is where your pages rank on search engine results pages (SERPs).

If the mobile version is stripped down, slow, or hard to navigate, Google treats that as your primary experience. A flawless desktop site cannot compensate for weak mobile performance.

Shopify SEO Strategist Greg Bernhardt explains that Google began shifting toward this model in 2016, after seeing mobile usage overtake desktop. 

“They saw the device, cultural, technological change happening. They thought, OK, now we need to start crawling as people with mobile devices see it, not just on desktop,” Greg says. “Because they could say, ‘Oh, this site has a great desktop experience,’ when, you know, maybe a whole lot of people on mobile are looking at it and having a terrible experience. So that was going to give them some misreading on experiences.” 

The transition accelerated in 2018, and by 2023, nearly every site on the internet had been moved to mobile-first indexing.

Why mobile-first indexing matters for ecommerce

Optimizing for Google’s mobile-first indexing ensures your store ranks well, loads quickly, and converts mobile shoppers. The quality of your mobile experience matters because:

• Most shoppers access websites on mobile

• Mobile users have shorter, more distracted sessions

• A poor mobile experience increases bounce rates; Google notices when users bounce and adjusts rankings accordingly

If people get frustrated, they hit the back button and choose another search result, and Google notices that. Many merchants review only the desktop version of their online store and assume it works the same on mobile. Greg warns that this is rarely the case. Delivering a high-quality mobile experience requires rethinking navigation, layout, and scannability from the ground up.

Mobile-first indexing best practices

1. Use responsive web design principles
2. Maintain content parity between mobile and desktop versions
3. Improve mobile speed
4. Remove unnecessary elements
5. Design for mobile UX
6. Test your store on multiple devices
7. Monitor mobile performance regularly

Follow these best practices to optimize your site for Google’s mobile-first indexing standards:

1. Use responsive web design principles

Responsive web design—meaning your layout automatically adapts to different screen sizes and resolutions—is the foundation of mobile-friendly design. “That’s number one,” Greg says. “You have to have that. That’s like the big rock. If you don’t have that, nothing else really matters.”

Responsive design means:

• One unified theme, rather than separate ones for desktop and mobile versions

• One URL per page (not separate mobile URLs)

• One codebase with a single set of files, rather than separate mobile and desktop codes

• Flexible layouts using Cascading Style Sheets (CSS) that let things grow and shrink naturally, and activate specific elements at certain screen sizes

Shopify themes are built to be mobile-friendly, but custom code or apps can break responsiveness. If your site isn’t responsive, no amount of speed optimization will fix mobile-first indexing issues.

2. Maintain content parity between mobile and desktop versions

Sometimes you may choose a simpler mobile layout to make the site’s content more scannable on small screens. “Think critically about how people use desktop experience versus mobile. If they have 30 seconds on a packed subway, they don’t have time to process and scroll,” Greg says. 

Because Google indexes your mobile site, all important content—any information Google uses to understand and rank your pages—must appear on your mobile version, including:

• Product descriptions

• Reviews and FAQ pages

• Structured data

• Internal links

• Navigation menus

• Images and alt text

If Google can’t see it on mobile, it doesn’t count, and your ranking signals get weaker.

3. Improve mobile speed 

Fast mobile site speed is a top factor in both SEO and conversion performance. For example, a one-second delay can impact mobile conversions by up to 20%. Mobile users often experience weaker signals on older devices due to network upgrades, so your pages must load quickly regardless of conditions.

Improve your site’s performance by:

• Optimizing images (resize, compress, use WebP files)

• Removing files that stop the page from displaying until they finish loading—called render-blocking resources—such as large CSS files

• Deferring nonessential JavaScript

• Minimizing CSS

• Using browser caching—mobile users on cellular networks especially benefit from cached content, which reduces data usage and speeds up repeat visits

• Improving server response times

• Eliminating heavy desktop-only elements, such as auto-play videos, fancy animations, or huge hero images

Greg emphasizes testing speed repeatedly with tools like Google PageSpeed Insights, Chrome Lighthouse, and Core Web Vitals in Google Search Console to account for anomalies or fluctuations in network availability or server load.

“You want to probably run whatever tool you have a few times. Again, you may run it and you hit a huge bottleneck in the network,” he says. “And then you check it again in five seconds, and then you’re in the green again.”

4. Remove unnecessary elements 

Not every desktop element belongs on mobile. Some can hurt mobile performance, including:

• Sidebars that collapse into a long stack of widgets on mobile, forcing users to scroll past irrelevant content to reach what they came for

• Large embedded videos that use lots of data and slow page loads on cellular networks

• Decorative images that Google doesn’t learn anything from, such as filler stock images

• Complex interactive widgets that need scripts or animation to work 

• Hover-only menus, as hover doesn’t exist on touch screens and won’t open

If it doesn’t help the mobile user complete a task, consider removing it. Removing clutter improves both the user experience (UX) and speed—two things Google cares deeply about.

5. Design for mobile UX 

Mobile users behave differently from desktop users. They scroll, tap, and spend less time on pages—around two minutes on mobile versus five minutes on desktop.

“A lot of times there’s more frustration than good experiences,” Greg says. “It’s gotten a little better over the years, but there are so many considerations one needs to make when deciding what changes need to be made to make the mobile experience successful.”

To improve your site’s mobile UX:

• Use a hamburger menu or slide-out navigation

• Place calls to action (CTAs) high on the mobile page

• Break up long sections into short, scannable blocks

• Use large, tap-friendly buttons—a minimum of 48 by 48 pixels

• Reduce unnecessary scrolling

• Use sticky add-to-cart buttons that stay visible on the screen as the user scrolls

6. Test your store on multiple devices

Different devices produce different mobile experiences. Cross-device testing ensures consistent mobile-friendliness and avoids hidden UX issues. “Don’t just test the iPhone 17,” Greg says. “Your customers might be on a Pixel, and everything could look funky there.”

He recommends using Chrome DevTools for testing to ensure that the experience is consistent across all devices by using Chrome’s device toolbar to simulate various mobile devices. “In Chrome, right click inspect, and get the developer console up,” Greg explains. “You can select different mobile device resolution sizes to change what your site looks like for that [device].”

Additionally, testing on actual smartphones—if you have access to different models—can provide valuable real-world insights. Use analytics data to focus your testing on devices your customers actually use.

7. Monitor mobile performance regularly

Mobile-first optimization is not a set-it-and-forget-it task. “The big milestones are a new design, a redesign, or a [website] migration,” Greg says. “Any type of migration, whether it’s moving platforms or servers, moving designs, or making significant changes in designs—all those things can have different readings that you’ll want to make sure are fine.”

Re-test mobile performance when:

• Migrating themes

• Installing or removing apps

• Updating navigation or footers

• Redesigning pages

• Changing hosting or content delivery network (CDN) providers

Greg recommends a quick weekly check. “Even if you didn’t change anything, your hosting provider might have,” he says.