Core Web Vitals: Enhancing User Experience and SEO Ranking

Discover how improving Core Web Vitals can optimize user experience and boost your website’s search engine ranking. Learn more about key metrics, tips, and best practices in this comprehensive article.

In the world of website optimization, delivering a seamless user experience while meeting search engine requirements is paramount. Enter Core Web Vitals – a set of metrics introduced by Google that aims to assess and enhance user experience based on real-world performance data.

By analyzing three key aspects of web page loading, interactivity, and visual stability, Core Web Vitals provides valuable insights into optimization opportunities. In this article, we will delve into what Core Web Vitals are, their importance in achieving better search engine ranking, and practical tips to improve them.

Understanding Core Web Vitals

Core Web Vitals are a set of three metrics that measure the real-world user experience of loading performance, interactivity, and visual stability of the page.

What are Core Web Vitals?

A set of three metrics that measure loading performance, interactivity, and visual stability of a webpage. They reflect real-world user experience and are considered important ranking factors by Google.

Core Web Vitals encompasses three core metrics:

  1. Largest Contentful Paint (LCP): LCP measures how long it takes for the largest content element on a page to load. It measures the time taken for the largest element on the screen to become visible to users. This metric focuses on user experience, as a quick loading time is essential for engagement.
  2. First Input Delay (FID): FID measures how long it takes for a browser to respond to the user’s first interaction with a page. It quantifies the responsiveness of a webpage by measuring the time gap between a user’s interaction (such as clicking a button) and the subsequent response from the website. A low FID ensures a smooth and interactive browsing experience.
  3. Interaction to Next Paint (INP): Replacing FID as a Core Web Vital metric in March 2024. INP measures the time between a user interaction and the browser painting the response, providing a more accurate gauge of responsiveness.
  4. Cumulative Layout Shift (CLS): CLS measures the amount of unexpected layout shift of visible elements on a page. This metric gauges the visual stability of a webpage by measuring the amount of unexpected layout shifts that occur. CLS accounts for the frustration users experience when elements unexpectedly move, potentially leading to inaccurate clicks or undesirable actions.

Why are Core Web Vitals Important?

Core Web Vitals have gained significant importance due to Google’s integration of these metrics into their search engine ranking algorithm. By prioritizing a positive user experience, Google aims to reward websites that provide fast-loading, responsive, and visually stable content. Ensuring good Core Web Vitals scores can directly impact your website’s visibility in search engine results and ultimately drive more organic traffic.

Core Web Vitals are important because they can have a significant impact on user experience. For example, studies have shown that pages with good Core Web Vitals tend to have higher conversion rates and lower bounce rates.

Google has announced that Core Web Vitals will become a ranking factor in Google Search starting in May 2023. This means that websites with good Core Web Vitals will be more likely to rank higher in search results.

Improving Core Web Vitals

Tips for Optimizing LCP

Here are key tips to optimize Largest Contentful Paint (LCP) in Core Web Vitals, along with visual aids:

  1. Optimize Images:
    • Compress images: Use tools like TinyPNG, Squoosh, or EWWW Image Optimizer to significantly reduce file sizes without noticeable quality loss.
    • Choose appropriate image formats: Opt for WebP or AVIF for next-gen compression, or JPEG 2000 for high-quality images.
    • Resize images: Scale images to match their display dimensions to avoid unnecessary loading of large files.
    • Implement lazy loading: Delay loading images below the fold until users scroll to them, improving initial load time.
  2. Minimize Render-Blocking Resources:
    • Defer non-critical JavaScript: Move non-essential JavaScript to the end of the HTML or load it asynchronously.
    • Minify CSS and JavaScript: Reduce file sizes by removing whitespace and comments.
    • Inline critical CSS: Include essential CSS directly in the HTML head for immediate rendering.
  3. Leverage Browser Caching:
    • Set appropriate cache headers: Instruct browsers to cache static assets (images, CSS, JavaScript) to reduce server requests.
  4. Utilize a Content Delivery Network (CDN):
    • Distribute content globally: Store assets on servers closer to users for faster delivery.
  5. Improve Server Response Time:
    • Optimize server configuration: Ensure efficient server-side processing.
    • Upgrade hosting: Consider a faster hosting plan or a dedicated server if needed.
  6. Preload critical assets: Use <link rel="preload"> to prioritize loading of key resources.
  7. Minify HTML: Reduce HTML file size by removing unnecessary elements.
  8. Reduce the number of network requests: Combine files and minimize redirects.
  9. Monitor LCP performance: Use PageSpeed Insights, Lighthouse, or the Core Web Vitals extension to track progress.

Tips for Enhancing INP

  1. Prioritize JavaScript Optimization:
    • Minimize JavaScript Execution Time: Break down large tasks, use Web Workers for background tasks, and avoid resource-intensive scripts.
    • Code Splitting: Divide code into smaller, loadable chunks based on user interactions.
    • Minification and Compression: Reduce file sizes using tools like UglifyJS and Brotli.
    • Defer Non-Essential Scripts: Load scripts that aren’t critical for initial rendering later.
  2. Reduce Main Thread Work:
    • Minimize Long Tasks: Break down long tasks into smaller chunks using requestIdleCallback or setTimeout.
    • Utilize Idle Time: Schedule tasks during user inactivity via requestIdleCallback.
    • Offload Work to Web Workers: Shift heavy computations to Web Workers to avoid blocking the main thread.
  3. Optimize Critical Rendering Path:
    • Minimize Render-Blocking Resources: Defer non-critical CSS and JavaScript, inline critical CSS, and preload key resources.
    • Optimize Loading Order: Prioritize loading elements above the fold and critical resources first.
  4. Address Layout Shifts:
    • Use Size Attributes for Images and Videos: Prevent layout shifts by reserving space with width and height attributes.
    • Leverage Placeholder Elements: Maintain layout stability during content loading using placeholder elements.
    • Minimize Dynamic Font Loading: Load fonts that are essential for initial rendering or use font-display options for smoother transitions.
  5. Implement Efficient Rendering Strategies:
    • Server-Side Rendering (SSR) or Static Site Generation (SSG): Pre-render content on the server for faster initial load and improved INP.
    • Minimize DOM Size and Complexity: Reduce the amount of HTML, CSS, and JavaScript to improve rendering speed.
    • Use Content-Visibility API: Lazy-load offscreen content to minimize initial rendering work.

Tips for Minimizing CLS

Here are some key tips to minimize CLS (Cumulative Layout Shift) in Core Web Vitals:

1. Reserve Space for Media Elements:

  • Set explicit width and height attributes for images and videos: This ensures the browser can allocate space for them before they load, preventing layout shifts.
  • Use CSS aspect ratio boxes for images: This allocates space based on the image’s aspect ratio, even before its dimensions are known.

2. Avoid Unexpected Layout Shifts Due to Ads, Embeds, and Iframes:

  • Preload or preconnect to third-party resources: This can speed up loading times and reduce layout shifts.
  • Use placeholders or skeleton screens for dynamic content: This provides visual stability while content loads.
  • Consider fixed-size dimensions for ads and embeds: This prevents them from causing layout shifts when their content changes.

3. Optimize Font Loading:

  • Use the font-display: swap property: This allows text to be displayed using a fallback font initially, preventing layout shifts when the custom font loads.
  • Consider preloading or preconnecting to font files: This can speed up font loading and reduce layout shifts.
  • Minimize the number of custom fonts used: Each custom font adds to the potential for layout shifts.

4. Minimize JavaScript-induced Layout Shifts:

  • Defer non-critical JavaScript: This prevents JavaScript from blocking rendering and potentially causing layout shifts.
  • Minimize the use of DOM manipulation: Avoid frequent changes to the DOM structure, which can trigger layout shifts.
  • Use requestAnimationFrame for animations: This ensures animations are synchronized with the browser’s rendering cycle, reducing layout shifts.

5. Leverage Browser Caching:

  • Implement caching strategies: This allows resources to be loaded from the cache on subsequent visits, reducing layout shifts.
  • Ensure pages are eligible for the back-forward cache (bfcache): This allows pages to be instantly restored when navigating back and forth, eliminating layout shifts.

Interaction to Next Paint

Here’s a comprehensive explanation of Interaction to Next Paint (INP) in Core Web Vitals:

What is INP?

  • INP is a metric that measures the responsiveness of a webpage to user interactions.
  • It assesses the time it takes from when a user interacts with an element (clicks, taps, etc.) to when the browser paints the visual response to that interaction.
  • It’s slated to replace First Input Delay (FID) as a Core Web Vital in March 2024.

Why is INP important?

  • A slow INP can lead to a frustrating user experience, as users may feel like the page is unresponsive or laggy.
  • Google considers INP to be a ranking factor, so a good INP score can potentially lead to better search rankings.

How is INP measured?

  • INP is measured in milliseconds (ms).
  • A good INP score is considered to be 200ms or less.
  • It’s measured using the Event Timing API, which tracks the timestamps of various events during user interactions.

Key components of INP:

  1. Input Delay: The time between when the user interacts with the page and when the browser starts processing the event.
  2. Processing Time: The time it takes for the browser to execute the code associated with the event.
  3. Presentation Delay: The time it takes for the browser to render the visual changes resulting from the interaction.

How to optimize for INP:

  • Break up long tasks: Divide long-running JavaScript tasks into smaller chunks to prevent them from blocking the main thread.
  • Minimize JavaScript execution time: Optimize JavaScript code, defer non-critical scripts, and use techniques like code splitting.
  • Use efficient event handlers: Avoid unnecessary event listeners and use efficient event handling techniques.
  • Optimize rendering: Minimize layout shifts and paint times by using techniques like avoiding layout-blocking resources and minimizing DOM size.
  • Leverage browser features: Use features like requestIdleCallback and requestAnimationFrame to schedule tasks for optimal performance.

Tools for measuring INP:

  • Chrome DevTools: Use the Performance panel to measure INP in real-time.
  • PageSpeed Insights: Check your INP score in the lab and field data sections.
  • WebPageTest: Measure INP as part of your overall performance testing.

Additional tips:

  • Prioritize interactions that are critical to the user experience.
  • Test your INP score on different devices and network conditions.
  • Use a performance budget to track your progress and set goals.


Core Web Vitals serve as an essential framework for website owners and developers to focus on providing exceptional user experiences. With Google’s emphasis on these metrics, optimizing LCP, NIP, and CLS is crucial to improve your search engine rankings and attract more organic traffic.

By continually monitoring and optimizing your website’s performance based on these key metrics, you will not only satisfy search engine requirements but also provide a fast, interactive, and visually pleasing experience for visitors. So, start implementing the tips mentioned in this article today, enhance your Core Web Vitals, and unlock the potential for better SEO success.

In addition to Core Web Vitals, Google is also considering other page experience signals, such as HTTPS, mobile-friendliness, and lack of interstitial pop-ups. These signals may also be used in Google Search ranking in the future.

Remember, a well-optimized website does not only bring visibility but also keeps visitors engaged and satisfied. It’s time to make your website stand out!