We explain what Core Web Vitals are and show how you can improve your CWV score on your Shopify store. ,
There’s plenty of information online about how to measure Core Web Vitals and whether your site is scoring well or poorly. But there’s very little actionable advice about what you need to do to make improvements, specifically on Shopify.
In this article, we’ll look at how exactly you can improve your Core Web Vitals score on your Shopify store. We’ve tried to make as many of these recommendations actionable without a developer, but some require expert technical implementation.
We’ll break down each core web vital metric in turn, explain what factors affect their performance, then show you how to improve each CWV metric on any Shopify store.
What Are Core Web Vitals
Core Web Vitals (CWV) refer to a set of key performance metrics created by Google to measure how a webpage actually feels for users. Core Web Vitals don’t just measure speed, they evaluate how quickly important content loads, how visually stable the page is while loading, and how responsive it feels when a user interacts with it. In other words, Core Web Vitals help determine whether your site delivers a smooth, user-friendly experience from the moment someone lands on your pages.
There are three primary Core Web Vitals metrics that every Shopify store owner should understand:
1 – LCP – Largest Contentful Paint
LCP measures how long it takes for the largest visible element on a page, usually a hero image, product image, or a large block of text to appear. A fast LCP ensures that users see meaningful content quickly, which helps reduce bounce rates and improves the overall user experience. On Shopify, optimising images, preloading key elements, and minimising render-blocking resources are common ways to improve LCP.
2 – CLS – Cumulative Layout Shift
CLS measures how much the layout shifts as a page loads. Unexpected movement, such as text jumping down the page or buttons moving as images load, can frustrate users and lead to accidental misclicks. Minimising layout shifts requires using explicit sizing for images and embeds, keeping layouts stable, and limiting the use of animations that could move content around.
3 – INP – Interaction to Next Paint
INP evaluates how responsive a page feels when a user interacts with it, such as clicking a button or opening a menu. This metric has become increasingly important on Shopify and now replaces the older First Input Delay (FID). Improving INP usually involves reducing JavaScript weight, deferring non-essential scripts, and keeping themes and apps lean, ensuring that the site reacts quickly to user actions.
Each page load is evaluated for each Core Web Vital metric and ranked as “Good”, “Needs Improvement”, or “Poor.” For a Shopify store to be considered to be performing well, the majority of its URL loads should meet the standard of “Good”. Consistently achieving this ensures a faster, more stable, and user-friendly experience across your site.
How Core Web Vitals Are Calculated On Shopify
It’s important to understand how Google calculates Core Web Vitals scores because this affects how to make meaningful improvements. The data for Core Web Vitals comes from CrUX data which measures the performance for real website visitors using the Chrome web browser. This is called ‘field data’.
For each CWV metric, there’s a minimum average score you need to hit to not be marked as ‘Poor’. This is based upon the average scores recorded against groups of pages. It’s important to understand that your Shopify website isn’t scored against a core web vitals metric; the URLs on your website are.
When your Shopify store fails on a Core Web Vitals metric, Search Console will show you a sample of URLs that were affected by the problem. This helps you narrow down where the issue is and apply target improvement. Before beginning any Core Web Vitals optimisation work on your Shopify store, first identify which areas of improvement will be most impactful. Don’t waste your time on work that won’t produce a positive result.
How Do Core Web Vitals Impact Google Rankings and Your Shopify Store’s Success?
Core Web Vitals are no longer optional, as they directly influence both your store’s user experience and its search performance. Poor scores can lead to slower page loads, layout shifts, and delayed interactivity, which frustrates users and can lead to reduced conversions. On the other hand, optimising these metrics helps your store rank higher on Google, keeps users engaged, and supports long-term growth by providing a smooth, reliable shopping experience.
- Ranking Impact: Google considers Web Vitals when ranking sites. Stores with poor performance risk being outranked by faster competitors, even if content and products are comparable.
- User Experience and Conversions: A slow or unstable store frustrates customers, and poor LCP means they wait too long for content, leading to higher bounce rates. High CLS can cause misclicks or confusion, and poor INP means interactions (such as Add To Cart) feel sluggish, lower sales and impact brand trust.
- Paid Marketing and Long-term SEO Value: Slow stores mean wasted ad spend (with users dropping before the page has time to load), lower conversion rates, and poor user retention, even if traffic is high to begin with.
- Competitive Advantage and User Trust: A fast, stable store instils confidence in a customer. This particularly matters for first-time customers and those returning, as e-commerce user experience is a key part of your brand.
In short, improving your Core Web Vitals is a foundational business requirement for UX, SEO and overall business performance.
How To Measure Core Web Vitals Performance
Before you fix anything, you need to know where your Core Web Vitals performance currently stands. Here are the main tools and methods to measure CWV on your Shopify store.
Search Console
If your Shopify store is connected to Google Search Console (GSC), you can access the Core Web Vitals report, which shows which URLs are rated as “Poor,” “Needs Improvement,” or “Good.” This report provides a broad overview of your store’s performance and helps you quickly identify problem areas, whether that’s specific pages, page types, or templates. Beyond just identifying issues, the GSC report allows you to prioritise optimisations, so you can focus first on pages with the highest traffic or the greatest potential for conversions. By tackling the most impactful pages first, you can make measurable improvements to user experience and search performance without needing to optimise your entire site at once.
Using PageSpeed Insights
PageSpeed Insights (PSI) is a free tool from Google that lets you test any page URL. It provides lab data, which simulates page speed and structure, as well as real-user metrics based on actual visitor experiences. PSI also highlights the Largest Contentful Paint (LCP) element, identifies any layout-shift issues, and shows which JavaScript or CSS resources are blocking rendering. With this detailed information, you can pinpoint exactly what needs fixing and start making targeted improvements to your store’s performance.
Using Lighthouse
Lighthouse is a performance auditing tool built into modern browsers like Chrome, making it a quick and convenient way to evaluate your site’s pages. It highlights issues such as render-blocking resources, inefficient scripts, unused CSS, heavy images, and other factors that can negatively affect LCP, CLS, and INP. Lighthouse is particularly useful when assessing new themes or before making significant changes to your store, as it gives you a clear snapshot of where performance improvements are needed. By using Lighthouse regularly, you can pinpoint bottlenecks, optimise your site more effectively, and ensure that your Shopify store provides a fast, smooth experience for users.
Using The Chrome User Experience Report (CRuX)
The Chrome User Experience Report (CRux) can give you insight into how your store performs over time and across different devices. For Shopify stores, native web performance dashboards or third-party dashboards can surface CRuX data aggregated across your store, giving you insight into your performance over time and across different devices.
Using these various tools periodically, but especially after any theme updates, app installs or major changes to your site, will help prevent performance regression and improve your site health over time.
Improving Web Performance on Shopify
Improving Core Web Vitals on Shopify essentially means improving your overall web performance. Here’s how to do that on Shopify, depending on the kind of optimisation you need.
Improving Largest Contentful Paint (LCP)
- Use appropriate optimised hero/product images: Convert images to the correct formats, keep file sizes small and ensure these are suitable for screen/responsive displays. Many Shopify themes manage image optimisation automatically, but it is always worth checking.
- Ensure the LCP element loads early: If the main image or content doesn’t load properly or is injected via JavaScript after the initial load, LCP will suffer. Avoid lazy-loading the LCP element if it appears above the fold.
- Preload the LCP resource: You can add a preload hint (e.g.) in your theme’s head so that the browser prioritises it. On Shopify’s Liquid themes, you can also use filters to output a preload tag.
- Reduce render-blocking resources: JS and CSS that lock the main thread delay the page from painting. Defer or async non-critical scripts, inline critical CSS, and delay or remove unused CSS and styles.
- Ensure the LCP element is in initial HTML: If your hero/product image is only inserted via JS page load, the browser can’t start fetching it until after JS runs, which hurts performance. It’s better to have any essential elements needed in the HTML output itself.
Improving Cumulative Layout Shift (CLS)
- Explicitly set width/height aspect ratio on images: By defining these dimensions in your HTML, the browser knows how much space to reserve before the image loads, which will prevent any shifts in the layout. On Shopify, this means editing the theme template Liquid template so image tags output something like width=”{{img:width}}” height=”{{img.height}}.
- Preload or limit font usage: Including many custom web fonts or loading them late may cause text to re-render when the font loads. To reduce layout shift, use limited font families, essential fonts and font-display strategies.
- Avoid animations that affect the page layout and dynamic content load: Animations (for example, sliding banners, popups, sticky elements or third-party widgets can distort your layout, causing CLS. Instead, opt for fade-ins or overlay widgets rather than ones that will shift the layout.
- Reserve space for dynamic components: If you use apps that inject corners (e.g. chat widgets, discount banners or popups), ensure these are placed in reserved containers to avoid shifting existing content when they load.
Improving INP / Interactivity
- Maximise JavaScript or third-party scripts: Heavy or poorly optimised scripts block the main browser’s thread and delay interactive readiness. Try using only essential scripts, remove any redundant ones and avoid stacking tracking widgets, review apps or other JS-heavy tools.
- Condense and defer scripts: Combine multiple tracking/tag scripts (e.g. Via google tag manager, remove duplicates and set non-critical scripts to load deferred or asynchronously, so initial load is faster, and intersection readiness improves.
- Choose lightweight themes and apps: Some themes and apps introduce a lot of DOM elements, extensive JS or heavy styles. All of these slow interactivity, so choose modern performance-optimised themes, and if you’re building anything custom, follow best practices to ease the execution of the workload.
- Audit thread work and long tasks: Use Lighthouse to identify any long-running JS tasks. If any script runs for more than 50-100ms, it may contribute to a sluggish interactive experience, so consider splitting or deferring the script to improve performance.
Core Web Vitals FAQ
Are Core Web Vitals the only factors that affect website performance?
No, while Core Web Vitals are key to website performance and user experience, other factors also matter. Some of these are:
- Mobile-friendliness and responsive design
- Secure connections (HTTPS), safe browsing and the absence of intrusive interstitials (e.g. any popups that block content), which also affect user experience under Google’s broader “page experience” criteria.
- Content relevance
- SEO best practices
- Website accessibility
- Server response times and stability under load also impact overall performance and user satisfaction.
Should I prioritise improving all Core Web Vitals equally?
You don’t have to prioritise improving all your Core Web Vitals at once, as priorities may vary depending on what issues your store is currently facing. For example:
- If your store is slow to load main content and hero/product images, you should first focus on improving LCP
- If you observe layout shifts or misclicks, CLS should be addressed as soon as possible
- If the store loads but remains unresponsive, INP should be reviewed promptly
In many cases, improving LCP and CLS delivery is the most immediate win. Once these are under control, working on INP is a logical next step for your Shopify store.
Are there any apps, coding tweaks or theme adjustments that are effective?
Yes, many Shopify store owners see significant improvements using a combination of careful theme configuration, code tweaks and app selection. For example:
- Using specific Shopify themes that are built with performance in mind
- Where possible, convert images to efficient formats (e.g. WebP), use responsive image sizes and preload hero or product images
- Inline critical CSS, defer non-critical CSS and JS, and remove unused styles and scripts.
- Limit the number of third-party apps, as each app may add JS/CSS widgets, and resources can slow load times or shift the layout.
- Consolidate tracking/pixel scripts instead of adding several different ones.
- Reserve UI space for dynamic content (popups, banners, etc.) or use overlay patterns that won’t affect the layout.
If you’re not comfortable editing theme code yourself, or if you want a thorough audit of both visible and behind-the-scenes issues, a professional optimisation service can help. Experts can safely implement fixes, ensure your store remains stable, and optimise performance without risking downtime or errors. This allows you to focus on running your business while your store runs smoothly and efficiently.
How to Maintain and Monitor Ongoing Web Performance
Improving Core Web Vitals isn’t a one-time task, as new products, store updates, app installments and theme changes can often introduce regressions. To maintain consistent performance, consider the following:
- Use your Shopify Web Performance Dashboard or the Google Merchant Centre to regularly monitor LCP, CLS, and INP across all page types.
- Re-run audits after any significant changes to your site, including new themes, app installs/uninstall or major design changes.
- Adopt a “performance-first” mindset by treating any change, whether that be a new image, a new script or a layout change, as an opportunity to assess its impact on performance.
- Clean up and remove any unused scripts, assets or app code, as dormant resources can still slow down your pages.
Summary & Key Takeaways
Core Web Vitals play a major role in your Shopify store’s user experience, SEO, conversion rates, and long-term success. By measuring performance regularly, you can see exactly where you stand and identify which improvements to prioritise.
Optimising LCP typically involves serving efficient, preloaded images and minimising render-blocking resources. CLS improvements come from using explicit sizing, maintaining stable layouts, and keeping animations under control. Meanwhile, INP can be enhanced by reducing JavaScript weight, deferring non-essential scripts, and keeping your theme and apps as lean as possible.
Performance isn’t a one-time fix for any Shopify store, think of it as an ongoing part of your site maintenance. Every update you make, whether it’s adding an app, changing a theme setting, or launching new content, is an opportunity to optimise and keep your store running smoothly.
While many improvements can be handled in-house, professional support can help speed up the process, especially when code-level adjustments, theme refinements, or deeper app audits are required. If you’re looking to improve your user experience, book a call with our expert team today.
If you need any advice or support with your ecommerce business, drop our team a line and we’d be happy to help.
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We are one of the world’s most trusted and experienced Shopify Plus Partners. A full-service, fully in-house digital agency of over 50 talented people, we’ve helped hundreds of ambitious brands exceed their goals.
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Eastside Co leads the way in UX-focused Shopify web design, results-driven marketing strategies, and best-in-class Shopify applications and software. We help online businesses escape the ordinary and achieve ecommerce success.
