When visiting a website, we expect it to be more than just a collection of pages, we expect it to be a great experience,
with good speed, stability, and smooth interaction. In that note, Core Web Vitals are a set of website performance
metrics that define that kind of user experience.
Google within its standards uses these metrics to measure how quickly content loads, how responsive a page feels, and
whether or not visual elements shift unexpectedly as the site renders. The key indicators are Largest Contentful Paint
(LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS), the three of them help determine whether a site is
performing at its best or falling behind. Google categorizes these metrics as Good, Needs Improvement, or Poor, which
results impacts on the overall website’s visibility in search results.
Credits: web.dev
As we move into 2025, user expectations continue to rise. Users are not just looking at the design anymore, they look
for a website that efficiently responds to actions and remains stable while loading. A sluggish or unstable website
frustrates visitors, reducing engagement, hurting conversions, and affecting search rankings.
In this guide, we will break down what are Core Web Vitals, their impact on SEO, how to measure them, and ways to
optimize performance. We’ll also explore real-world case studies of businesses that improved these website performance
metrics and saw meaningful results.
It’s important to remember that neglecting any of these metrics can harm your website rankings, but also reduce
conversions. So, track performance results for a better user experience and stronger rankings.
Want a faster, more reliable website? Then let’s begin.
Understanding Core Web Vitals
Google Core Web Vitals and they are Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). They are made to measure the user experience of a website. These metrics focus on 3 real life (or field) aspects of user experience:- Loading: How quickly the main content of a page loads (LCP).
- Interactivity: How fast a website responds to user interactions (FID).
- Stability: How visually stable the content is as it loads in the browser (CLS)
- Higher search engine rankings: Google uses these metrics as part of its ranking criteria.
- Lower bounce rates: A smooth, responsive experience keeps users engaged.
- Higher conversions: Fast-loading and stable pages increase the likelihood of user actions.
The Impact of Core Web Vitals on SEO & User Experience
How your website performs in Core Web Vitals can impact your user experience and your ranking potential. Because your website should provide a fast, smooth, and enjoyable experience for users.And Google aims to reward content that provides users with this kind of great experience. Google Core Web Vitals are these factors touted as being critical for all web experiences, and address e.g. loading experience, interactivity, and visual page content stability. As you might know, all these factors are crucial since they play an important role in user engagement, conversion rates, and search engine optimization (SEO) rankings.
How Slow Loading Times, Poor Interactivity, and Unstable Layouts Harm Your User Engagement and Conversion Rates
Slow Loading Times (LCP): Slow and steady might have helped the turtle win the race, but when it comes to websites, even a second of delay spells a loss of user engagement, conversions, and retention.
When your website’s primary content takes too long to load, users in most cases become impatient and leave.
More accurately:
- 53% of mobile users abandon a site that takes longer than 3 seconds to load.
- A 1-second delay in page load time can lead to a 7% reduction in conversions.
Poor Interactivity (FID): is a user-focused metric that evaluates the speed of loading and gauges the experience users encounter when trying to engage with pages that fail to react.
As both the Google guide and web.dev’s insights highlight, FID calculates the duration between a user’s initial action on a page (such as clicks, taps, or form entries) and the instant when the browser finally reacts to the input.
From a technical perspective, it represents the duration, measured in milliseconds, that passes between the user’s first action on a webpage and the browser’s reaction to that input.
If you want to use an analogy, FID is like timing the gap between when someone presses a doorbell and when the door is answered. Most likely, if no response follows, people move on.
Additionally, it should be noted that sites with an FID of 100 milliseconds or less benefit from improved rankings.
Unstable Layouts (CLS): CLS as one of the website performance metrics calculates the visual stability of a webpage during the loading process. It quantifies the amount of unexpected shifts in page content that occur as the page loads and is crucial for assessing the user experience.
Unexpected shifts in page content represent involuntary movement, unconsented actions, and surprise alterations that catch users off guard and disrupt the browsing experience.
Unlike the previous two metrics, CLS isn’t measured in seconds or milliseconds. A good CLS is considered anything below 0.1.
So, how is CLS affecting your conversion rates?
It’s simple: unexpected shifts in page content disrupt the user experience— from causing the user to lose their place while reading to making them click the wrong link or button.
In both cases, the layout changes cause frustration, leading to users immediately leaving your web page.
Direct Influence on SEO Rankings
Google clearly states that it considers Core Web Vitals when ranking pages in search results. This makes them a direct ranking factor. That’s due in part because websites with faster load times and better user experiences tend to retain visitors longer. So, improving Core Web Vitals improves your website’s rankings in search engine results pages as:
- They provide better experiences. A positive user experience lowers bounce rates and indicates to search engines that a site is more relevant and of higher quality.
- They have higher conversion rates. Sites optimized on Google Core Web Vitals tend to have higher conversion rates, a metric that search engines incorporate when determining SEO rankings.
- They are better for search engine crawlers. Optimizing for Core Web Vitals enables faster loading times. This helps search engine crawlers to index more pages faster, potentially increasing visibility in search results.
Case Studies Demonstrating Performance Improvements
Vodafone had issues with the performance of its website. They noticed that the Largest Contentful Paint (LCP) metric was slow, and that meant the main content of the page was taking a longer time to load. This issue harmed user experience and sales. But by focusing on server-side rendering of critical HTML, reducing render-blocking JavaScript, and optimizing images, Vodafone improved their LCP by 31%.
These improvements led to an 8% increase in sales, showcasing the direct correlation between Core Web Vitals optimization and business performance.
Credits: web.dev
The next case is that of The Economic Times, among the largest news sources with more than 45 million monthly active readers, refined its Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) to offer its audience an ideal experience. The final outcome was enhancing CLS by 250% to 0.09, LCP by 80% to 2.5 seconds, meeting Core Web Vitals, and, most importantly—cutting bounce rates by 43% overall.
Credits: web.dev
Measuring & Optimizing Core Web Vitals
As with everything, when you want to improve Core Web Vitals you need a clear plan. We suggest that you start the improvement process by measuring your current performance, analyzing the results, making optimizations, and continuously testing for improvements. Below is a guide to help you do that effectively, so follow it to get the best results.Step 1: Measurement Tools
First, you need to understand how your website is performing before making any improvements. Several free tools provide insights into Google Core Web Vitals:
- Google PageSpeed Insights: Enter a URL, and this tool will provide Core Web Vitals data along with recommendations for fixing performance issues. It shows both Lab Data (simulated tests) and Field Data (real user experiences).
- Lighthouse: A built-in Chrome tool that audits web pages for performance, accessibility, and best practices. Run it from Chrome DevTools (F12 > Lighthouse) to get detailed reports.
- Google Search Console (Core Web Vitals Report): In Google Search Console, the Core Web Vitals report can be found under the “Experience” section, but only if your site is verified. This report organizes your pages into three groups, “Good,” “Needs Improvement,” and “Poor”. With this report in hand, you will know which ones require optimization.
How to Use These Tools
-
Google PageSpeed Insights:
- Visit PageSpeed Insights.
- Enter your website URL and click “Analyze.”
- Review the scores for LCP, FID (or INP as a replacement metric), and CLS.
- Check the diagnostics for suggestions on improvements.
-
Lighthouse:
- Open Chrome and go to your website.
- Press F12 to open DevTools, then navigate to the “Lighthouse” tab.
- Select “Performance” and click “Analyze.”
- Review the report to identify problem areas.
-
Google Search Console:
- Go to Google Search Console.
- Click on “Core Web Vitals” under the “Experience” section.
- View the report to find URLs that need improvement.
Step 2: Analysis & Interpretation
If your performance data has been gathered, you’ll have to analyze it under the next step. That will help you identify any issues.
- LCP measures the time it takes for the browser to load the largest visible element on a page (image, video, or text block) after the page has started loading. A high LCP means it’s too slow.
- FID (First Input Delay) – If this is poor, your page may be running heavy JavaScript, delaying interactions.
- CLS (Cumulative Layout Shift) – A high score means your content is moving unexpectedly, causing frustration for users.
How to Identify Problems
- PageSpeed Insights: Scroll down to the “Opportunities” and “Diagnostics” sections. These suggest ways to fix slow-loading elements.
- Lighthouse Report: Look at the performance breakdown and note high-impact issues.
- Search Console: Identify specific URLs that fail Core Web Vitals and prioritize them for fixes.
Step 3: Optimization Techniques
After identifying problem areas, apply targeted fixes.
Improving Largest Contentful Paint (LCP)
- Lossless Compression: This method reduces the file size without affecting the quality. It keeps hold of all the image data, which makes it perfect for graphics, logo,s and images that need.
- Use Lazy Loading: Load images only when they are needed by adding the loading "lazy" attribute.
- Leverage Browser Caching: Speed up future visits by keeping static files stored in the browser.
- Utilize a CDN: Distribute content across multiple servers, serve from the nearest location, and improve delivery speed.
Reducing First Input Delay (FID)
- Minimize JavaScript Execution: Avoid large JavaScript tasks that block the browser from responding to interactions.
- Defer Non-Essential Scripts: Use async or defer attributes on JavaScript files to prevent them from delaying content rendering.
- Optimize Third-Party Scripts: Remove unused third-party services that slow down page response times.
Fixing Cumulative Layout Shift (CLS)
- Set Image and Video Dimensions: Always define width and height attributes for media files to prevent layout shifts.
- Reserve Space for Ads & Embeds: Ensure advertisements and iframe elements have predefined space to avoid sudden content jumps.
- Use Font Display Strategies: Avoid Flash of Invisible Text (FOIT) or Flash of Unstyled Text (FOUT) by using font-display: swap in CSS.
Step 4: Testing & Iteration
Improving Core Web Vitals is an ongoing process. After making changes, test your site to see if improvements are effective.
How to Test Changes
- Use PageSpeed Insights Again: Run the same URL through the tool to check updated Core Web Vitals scores.
- Check Real User Data: Monitor Google Search Console for Core Web Vitals updates (data may take a few days to refresh).
- Compare Before and After: Note differences in LCP, FID, and CLS to measure improvements in website performance metrics.
Best Practices for Continuous Improvement
- Monitor Regularly: Google Core Web Vitals performance can fluctuate due to new content, plugins, or design changes. Run audits monthly.
- Optimize New Content: Ensure images, fonts, and scripts in new pages follow website performance metrics best practices.
- Keep Code Clean: Regularly remove unused CSS, JavaScript, and unnecessary elements to support improving Core Web Vitals.
Remember to use the right Core Web Vitals tools, and follow these strategies as they help improve your site’s speed, user experience, and overall SEO performance.
Real Examples & Case Studies
With numerous great case studies on Core Web Vitals available online, we have compiled the most well-known and trustworthy examples. No worries, you can easily browse through them and understand the benefits of website performance metrics and Core Web Vitals improvements in an instant!eBay
- Key takeaway: How eBay improved LCP by 40%, reducing bounce rates and increasing conversions
- Year published: 2023
- Source: Google Web.dev
- Optimized metrics: LCP
To improve LCP, eBay used server-side rendering (SSR) and switched to WebP for faster image loading. They also delayed non-essential scripts to speed up pages. These changes improved LCP by 40%, making pages load faster and reducing bounce rates. The company also saw an increase in completed purchases as users stayed engaged longer.
DeeZee
Credits: hatimeria
- Key takeaway: Reduced CLS by 45%, improving readability and engagement
- Year published: 2024
- Source: Google Web.dev
- Optimized metrics: CLS
To address this, DeeZee collaborated with Hatimeria to reserve fixed spaces for ads, preload fonts, and optimize CSS delivery, stabilizing the site's layout. These efforts led to a remarkable 96% reduction in CLS, enhancing readability and user engagement. Post-optimization, the site experienced increased user retention, with visitors exploring more products per session and interacting with content more seamlessly.
Shopify
Credits: renderbetter
- Key takeaway: Doubled conversion rate and reduced checkout abandonment by optimizing FID
- Year published: 2025
- Source: Google Web.dev
- Optimized metrics: FID
To fix this, Shopify cut down JavaScript execution time, introduced lazy loading, and prioritized faster input responses. These changes reduced FID by 60%, making checkout smoother and doubling conversion rates. Fewer users abandoned their carts, and more completed their transactions without delays. Store owners reported faster site performance, leading to better customer satisfaction and increased sales.
As shown above, let’s bring together the key takeaways in one place:
Improved loading speed:
- eBay’s LCP improved by 40%, significantly reducing page load times.
- Faster loading resulted in a noticeable drop in bounce rates, keeping users engaged.
- Users experienced smoother navigation, leading to an increase in time spent on product pages.
- DeeZee reduced CLS by 96%, ensuring a stable browsing experience.
- Users spent more time on pages, interacting with products more smoothly.
- Fewer disruptions from unexpected layout shifts led to higher customer retention.
- Shopify’s FID optimization led to a 60% improvement in responsiveness.
- Cart abandonment decreased, and completed purchases significantly increased.
- A faster, more seamless checkout process contributed to improved customer satisfaction.
- Store owners reported better engagement and stronger long-term customer loyalty.
Conclusion & Final Tips
We hope by now it is clearer to you what are Core Web Vitals and how they affect how fast your site loads, how users interact with it, and where it ranks in search results. This guide covered LCP, FID, and CLS, showing how they impact user experience and conversions. The case studies highlighted businesses that made changes and saw real improvements.A structured, data-driven approach works best. Instead of guessing, measure your site’s performance, fix the problems, and test again. As above stated Google Core Web Vitals are not a one-time fix issue, they need regular monitoring to keep up with changes in technology and user expectations.
We suggest you stay informed about Google’s latest updates. Simple fixes, like improving images, reducing script delays, and stabilizing layouts, can make a big difference.
Now, take the next step. Run a Core Web Vitals test, review the results, and start optimizing. A fast, stable site improves user experience and helps your business perform better. Or , you can start improving Core Web Vitals with Ajroni. Ajroni's services will help you ensure that your customer experience is exceptionally delightful. Learn more about our services module here.
