Core Web Vitals: A Guide to Bookmark in Your Browser

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In recent years, Google has increasingly focused on user experience as one of the central pillars of website ranking. While ranking factors used to be predominantly semantic, performance and usability have now taken the spotlight. Within this context, Core Web Vitals metrics have emerged as essential for any site that wants to stand out in search results.

Launched in May 2020, Core Web Vitals were created to provide unified guidance on the key quality indicators of a web page. These indicators not only directly influence search engine rankings but also significantly impact user experience—a crucial factor for the success of any website.

If you need help optimizing your site, get in touch with Pink and Brain. We’re true experts when it comes to improving websites through Core Web Vitals metrics.

In this guide, we’ll explore in detail what Core Web Vitals are, how to measure them, which tools to use, and the best practices to optimize your website accordingly.

What Are Core Web Vitals?

Core Web Vitals are a set of standardized Google metrics that measure essential aspects of user experience on a web page. These metrics evaluate three main elements: loading speed, interactivity, and visual stability. Together, they provide a comprehensive view of how users perceive a site’s performance.

The Core Web Vitals consist of three primary metrics:

• Largest Contentful Paint (LCP): Measures the time it takes for the largest visible content element on the page to load.
• Interaction to Next Paint (INP): Evaluates how quickly the page responds to a user interaction.
• Cumulative Layout Shift (CLS): Checks the visual stability of the page by measuring unexpected layout shifts.

Key Core Web Vitals Metrics in 2024

These metrics were chosen by Google because they directly affect user experience, influencing both perceived speed and ease of use.

The First Input Delay (FID) metric was one of the first major UX metrics introduced by Google. It measured the time it took for a page to become interactive after a user’s first action.

However, FID is no longer part of Core Web Vitals as of 2024. Google replaced it with Interaction to Next Paint (INP), which provides a broader and more accurate view of page responsiveness.

Why Core Web Vitals Matter for SEO

Since Google integrated Core Web Vitals into the Page Experience Signals, these metrics have become critical for any SEO strategy.

So why are they so important?

• Ranking improvement: Websites offering better UX are more likely to stand out in search results.
• Lower bounce rates: Slow-loading or unstable pages drive visitors away. Optimizing Core Web Vitals reduces this risk.
• Higher conversion rates: A fast, seamless page is far more likely to turn visitors into customers.

Exploring the Core Web Vitals Metrics

Largest Contentful Paint (LCP) – Loading the Largest Visible Content

LCP measures the time it takes for the largest visible element on a page to load completely. This element can be an image, a video, or a text block. LCP is crucial because it reflects how users perceive site loading speed.

Common factors that affect LCP:

• Large or unoptimized images
• Slow server response times
• Complex client-side rendering

Recommended optimizations:

• Compress and modernize images (WebP)
• Use CDNs to reduce latency
• Preload critical resources with <link rel="preload">

Google recommends keeping LCP under 2.5 seconds for a good user experience.

Interaction to Next Paint (INP) – Page Interactivity

INP measures how quickly a page responds to a user interaction, such as a click or tap.

Common factors that affect INP:

• Heavy or poorly optimized JavaScript
• Long-running tasks blocking the main thread

Recommended optimizations:

• Minify JavaScript
• Break up long tasks
• Use Web Workers for heavy scripts

Google recommends keeping INP below 200 milliseconds for smooth experiences.

Cumulative Layout Shift (CLS) – Visual Stability

CLS measures how often elements on a page unexpectedly shift while loading.

Common factors that affect CLS:

• Images without defined dimensions
• Third-party ads and iframes
• Custom fonts loading asynchronously

Recommended optimizations:

• Always define width and height for media
• Reserve space for ads
• Use optimized web fonts (font-display: swap)

A good CLS score is 0.1 or less.

Tools to Measure Core Web Vitals

There are several tools to measure Core Web Vitals, both from Google and third parties, that help analyze and evaluate these essential metrics. Below are some of the most commonly used tools, many of which are free:

Google PageSpeed Insights

Google PageSpeed Insights is a widely used tool that provides data on Core Web Vitals for both mobile and desktop devices. Besides showing metric scores, it offers detailed suggestions to optimize page performance.

How to use:

1. Visit the PageSpeed Insights website.
2. Enter the URL of the page you want to analyze.
3. Click Analyze and wait for the results.

The report provides an overview of LCP, INP, and CLS scores, along with other performance metrics and improvement suggestions.

Example Analysis from Google PageSpeed Insights for the Express Remoções homepage:
The site previously had multiple loading issues and was built on WordPress using the Elementor plugin, which we do not recommend for projects requiring solid organic traffic. We rebuilt the site from scratch following semantic formatting and SEO best practices, focusing on key Core Web Vitals metrics. Today, the site loads almost instantly.

If you want to learn more, check out our tips for SEO optimization on WordPress sites.

Google Lighthouse

Google Lighthouse is an open-source auditing tool that can be used as a browser extension or directly via Chrome DevTools. Beyond Core Web Vitals, it evaluates other site aspects such as accessibility and SEO best practices.

How to use:

1. Open the page you want to test in Chrome.
2. Right-click and select Inspect.
3. Go to the Lighthouse tab and click Generate Report.

The report provides a detailed analysis of several metrics, including Core Web Vitals, and offers improvement recommendations.

Google Search Console

Google Search Console provides a comprehensive view of Core Web Vitals across all pages on your site. It allows webmasters to identify large-scale issues and monitor performance over time.

How to use:

1. Log in to Google Search Console.
2. Navigate to the Page Experience section in the side menu.
3. Click Core Web Vitals to view a detailed report of your pages’ performance.

Search Console categorizes pages as Good, Needs Improvement, or Poor based on Core Web Vitals. It also highlights which URLs require attention and provides direct links to fix identified issues.

Other Tools to Measure Core Web Vitals

• GTmetrix (PRO Plan): Offers advanced testing features, including Core Web Vitals measurement. Useful for monitoring and improving site performance based on Lighthouse data.
  Price: Plans starting at $10/month.
• Pingdom: Provides insights on page speed and Core Web Vitals monitoring with detailed reports and recommendations.
  Price: Plans starting at $10/month.
• WebPageTest (PRO Plan): Robust web performance analysis tool measuring Core Web Vitals and providing detailed performance data.
  Price: Plans starting at $15/month.
• Semrush (SEO Toolkit with Site Audit): Multifunctional SEO tool including site audit features for Core Web Vitals.
  Price: Plans starting at $129.95/month.
• Screaming Frog SEO Spider (Paid License): Powerful SEO tool that audits sites and identifies Core Web Vitals issues.
  Price: Paid license from £199/year.

Best Practices for Optimizing Core Web Vitals

Now that we understand the importance and tools to measure Core Web Vitals, it’s essential to know how to optimize your website to achieve good scores. Below are best practices for each metric:

Optimizing Largest Contentful Paint (LCP)

• Improve server response times: Choose fast, optimized servers and use CDNs like Cloudflare.
• Load CSS/JS asynchronously: Minimize blocking resources and load scripts/styles asynchronously.
• Prioritize above-the-fold content: Use Lazy Loading for below-the-fold elements and preload the heaviest resources above the fold.
• Optimize images: Use modern formats (e.g., WebP) and specify width and height to avoid reflows.

Optimizing Interaction to Next Paint (INP)

• Reduce heavy JavaScript execution: Minify and compress scripts.
• Use code splitting: Load only the necessary code per page.
• Web Workers: Offload heavy processing to maintain page responsiveness.
• Defer non-critical scripts: Load analytics, social widgets, or other non-essential scripts after initial interactions.

Optimizing Cumulative Layout Shift (CLS)

• Set dimensions for all media: Define width and height for images and videos.
• Use font-display: swap: Prevent reflows caused by custom fonts.
• Manage ad loading: Reserve layout space for ads and iframes; defer their loading.
• Avoid sudden dynamic content insertion: Animate transitions if adding dynamic elements like pop-ups or banners.

Can WordPress Sites Score Well on Core Web Vitals?

Definitely yes. Even as a PHP-based platform, WordPress can perform excellently when properly optimized. Use lightweight themes, minimal plugins, avoid heavy builders like Elementor, and follow semantic SEO practices.

For example, Pink and Brain rebuilt the Express Remoções website from scratch, achieving near-instant load times and excellent Core Web Vitals scores.

Check out our SEO optimization tips for WordPress sites if you have one.

Continuous Monitoring of Core Web Vitals

Optimizing Core Web Vitals is an ongoing process. As your site grows, new pages and content are added, making regular monitoring essential. Tools like Google Search Console and Google Analytics can alert you to performance drops or emerging issues.

Core Web Vitals reflect the actual user experience on your site. Ignoring them risks losing traffic and business opportunities. Optimizing these metrics improves Google rankings, enhances user experience, increases engagement, boosts conversion rates, and positively impacts business results.

If you need help optimizing your website, contact Pink and Brain. We’re experts in site optimization using Core Web Vitals.