Core web vitals have become crucial metrics that make or break website success since Google made them ranking factors in mid-2021. The data shows websites with poor performance metrics see major drops in search visibility. Sites that optimize speed and stability continue to improve their positions.
These critical measurements boil down to three key metrics: Largest Contentful Paint (under 2.5 seconds), Interaction to Next Paint (less than 200 milliseconds), and Cumulative Layout Shift (less than 0.1). Google uses tools like Chrome UX Report and PageSpeed Insights to assess your site’s performance. This piece explains why these metrics matter and shows you how to improve core web vitals so your website stays ahead of competitors.
What Are Core Web Vitals and Why Do They Matter
“Core Web Vitals is a set of metrics that measure real-world user experience for loading performance, interactivity, and visual stability of the page.” — Google Search Team, Google Search Documentation Team
Google’s Core Web Vitals show a basic change in website quality measurement. Traditional metrics looked only at loading times. These vitals review how users experience websites through three key areas of web performance.
Largest Contentful Paint (LCP)
LCP shows how fast the largest content element in your viewport loads. Your main content becomes visible to users at this point. The element could be an image, video, or large text block.
Website developers couldn’t accurately measure perceived loading speed over the last several years. Load or DOMContentLoaded metrics didn’t match what users saw on their screens. LCP fixes this by focusing on the appearance time of key content.
Your LCP score should stay at 2.5 seconds or less. Google’s guidelines say scores between 2.5 and 4 seconds need work, while scores above 4 seconds are poor. Fast LCP scores tell visitors your page works well and reduces bounce rates.
Interaction to Next Paint (INP)
INP took First Input Delay’s (FID) place in March 2024 as Google’s official responsiveness metric. This change brings a better way to measure interactivity.
FID only measured the first interaction. INP looks at all user interactions throughout the page’s life. It captures everything from the first input through event handling until the browser shows the next frame.
Good INP scores stay at 200 milliseconds or below. Scores between 200-500ms need improvement. Anything above 500ms is poor. These measurements matter because users spend 90% of their time on a page after it loads, making quick responses vital.
Cumulative Layout Shift (CLS)
CLS tracks visual stability by measuring unexpected movement of page elements during loading. These shifts frustrate users. People lose their place while reading or click wrong links.
The CLS score comes from multiplying two things: impact fraction (shifted visible content) and distance fraction (element movement distance). Keep your CLS score at 0.1 or less.
Poor CLS happens because of images without dimensions, self-resizing ads, dynamic content injection, and web fonts that look different from their fallbacks. High CLS scores hurt user experience badly. About 93% of people leave websites that don’t load right.
The best SEO results come from meeting the recommended thresholds for all three Core Web Vitals at the 75th percentile of page loads on mobile and desktop devices.
How Core Web Vitals Impact SEO and Rankings
“From June 2021, any web page not passing Core Web Vitals may lose its ranking, and be replaced by a page with a good page experience score.” — SEO Sherpa Team, SEO Agency and Web Performance Experts
Google announced a major change in their search algorithm in 2020. This change confirmed what many SEO specialists already knew – your website’s performance directly affects its ranking positions.
Google’s page experience update
Google officially confirmed that Core Web Vitals are a ranking factor in their page experience update. The update combined several signals like mobile-friendliness, secure HTTPS connections, and no intrusive interstitials. In spite of that, Google keeps emphasizing that content relevance matters more than speed.
Google wants 75% of your users to have a “Good” experience across all three Core Web Vitals metrics to boost your ranking. The Chrome User Experience Report (CrUX) provides this real-life data instead of lab test results.
Why does performance affect search visibility
The numbers from Google’s research tell a clear story: 53% of mobile sites lose visitors if they take more than 3 seconds to load. So, websites that load slowly often see higher bounce rates and their rankings drop over time.
Better Core Web Vitals won’t push you to the top spot if your content isn’t relevant. However, they can be the deciding factor when competing against equally relevant websites. Your rankings can improve even before you fully meet the thresholds.
Each metric has its targets:
- LCP: Below 2.5 seconds (Good)
- INP: Below 200 milliseconds (Good)
- CLS: Below 0.1 (Good)
Real-life ranking examples
Redbus fixed their Core Web Vitals and saw 80-100% increased mobile conversion rates along with better domain rankings worldwide. Their rankings improved across markets when they reduced CLS from 1.65 to 0.
Tencent Video’s click-through rates jumped 70% for videos after passing Core Web Vitals. Nykaa’s organic traffic from smaller cities grew 28% after they made LCP 40% faster.
Yahoo! Japan improved their CLS scores and saw amazing results. They reduced poor pages by 98% and increased page views per session by 15%. These numbers show how these metrics directly boost business results.
How to Measure and Monitor Core Web Vitals
Website owners need specialized tools to track Core Web Vitals in both lab and field environments. Google makes this task easier by offering several free tools that help you monitor these significant metrics.
Using Google Search Console
Google Search Console features a dedicated Core Web Vitals report that groups similar pages based on their performance. This feature becomes especially valuable if you have a large website with thousands of pages sharing the same templates.
The report gets real user data from the Chrome User Experience Report (CrUX) to show your pages’ real-life performance. Your site might be new to Search Console or might not have enough CrUX data if you see a “No data available” message.
The tool lets you click on specific issues to see which URL groups are affected. This helps you decide which templates or page types need your attention first.
PageSpeed Insights and Lighthouse
PageSpeed Insights gives you a complete view of your site’s performance by combining lab and field data. The tool reports all three Core Web Vitals metrics with easy-to-understand color indicators:
- Green (Good): LCP under 2.5s, INP under 200ms, CLS under 0.1
- Amber (Needs Improvement): LCP 2.5-4s, INP 200-500ms, CLS 0.1-0.25
- Red (Poor): LCP over 4s, INP over 500ms, CLS over 0.25
Developers can use Lighthouse through Chrome DevTools for a more technical approach. The tool reviews accessibility, best practices, and SEO alongside performance. Lighthouse gives immediate feedback during local development without waiting for field data collection.
Chrome UX Report (CrUX)
Google’s Core Web Vitals assessment relies heavily on the Chrome UX Report. This dataset contains anonymous performance data from real Chrome users who visit millions of websites.
Most Google tools, including Search Console and PageSpeed Insights, use CrUX data to report Core Web Vitals. While the data only covers Chrome users and sites with enough traffic, it provides exceptional insights into your website’s visitor experience.
The CrUX Dashboard in Looker Studio helps you analyze this data in detail across different dimensions like device types and connection speeds.
How to Improve Core Web Vitals Effectively
Web vitals optimization needs specific strategies for each metric. The measurement tools we discussed earlier help identify problem areas. These insights let you implement targeted optimizations that deliver lasting performance gains.
Optimizing LCP: images, CDNs, lazy loading
Image optimization plays a crucial role in faster Largest Contentful Paint. You should compress and resize images properly, then convert them to modern formats like WebP. These formats can be 30% lighter than JPEG equivalents. A Content Delivery Network (CDN) makes LCP much better by caching static content closer to users—within 100 milliseconds of 95% of internet users.
Lazy loading needs careful consideration. Research shows that lazy-loaded LCP elements make performance worse. You should only apply lazy loading to below-the-fold images and load above-the-fold content right away. The fetchpriority="high" attribute helps prioritize loading for critical LCP images.
Improving INP: reduce JavaScript, static pages
Too much JavaScript execution often hurts Interaction to Next Paint. Start by finding slow interactions through field data and Chrome’s Performance tab. The scheduler.yield() API helps break up long JavaScript tasks by yielding to the main thread.
JavaScript reduction matters most. Chrome DevTools’ coverage tool helps find and remove unused code. Heavy processing tasks work better with web workers or setTimeout callbacks. These update the UI before starting CPU-intensive work.
Fixing CLS: reserve space, size attributes, CSS aspect ratios
Elements without defined dimensions cause visual stability problems. Width and height attributes should be part of all images, videos, and iframes. Responsive images that keep their aspect ratio need this:
<img src="image.jpg" alt="Description" width="1600" height="900">CSS aspect-ratio property works great for non-image elements:
iframe {
aspect-ratio: 16 / 9;
width: 100%;
height: auto;
}Space reservation helps with dynamic content like ads or widgets. Use min-height and min-width properties. Font-display: optional prevents layout shifts during font loading with web fonts.
Conclusion
Your website’s search visibility and user experience depend without doubt on Core Web Vitals as vital performance indicators. This piece explores how Google uses these metrics to measure what users experience on your site. Better rankings come from optimizing LCP to under 2.5 seconds, INP to under 200 milliseconds, and CLS to under 0.1.
The business value behind these technical improvements shows up clearly in real-life examples. Mobile conversion rates jumped 80-100% for Redbus after they fixed their Core Web Vitals. Tencent Video saw their click-through rates improve by 70%. These results show how better performance leads directly to more revenue and user participation.
Google’s tools make it easy to track these metrics. You can get big-picture insights for your whole site through Search Console. PageSpeed Insights gives specific recommendations for each page. You don’t need special knowledge or expensive software to start measuring performance today.
The good news is that you won’t need to rebuild your website completely. Your scores can improve dramatically with simple techniques. Properly sized images, minimal JavaScript, and reserved space for dynamic content work well. Getting “good” ratings across all three vitals might seem tough at first, but the competitive edge makes it worth the effort.
Note that you’ll see ranking benefits even before hitting all thresholds. Users notice your brand through your website’s performance. Core Web Vitals optimization isn’t just for SEO – it’s a basic business need. Start making these changes now and you’ll likely see better rankings, fewer bounces, and end up with more conversions.