Core Web Vitals Explained: LCP, INP and CLS

Trevor Dove, CEO Jan 12, 2024
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Technical guidance reviewed October 29, 2026. The original publication date is retained. INP replaced FID as a Core Web Vital on March 12, 2024.

Understanding Google Core Web Vitals

If your website isn't converting as expected, performance is one area to investigate alongside the offer, content and contact path. Core Web Vitals measure loading performance, responsiveness and visual stability. They are individual metrics, rather than one combined score. The current metrics are Largest Contentful Paint (LCP), Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS). Google's Web Vitals guide explains the measures and their field-data assessment.

Why These Measures Matter

These measures are useful for several reasons:

  • Enhanced User Experience: Better loading, responsiveness and stability can make a website easier to use. Measure the actual visitor journey and inquiries before claiming that a performance change improved satisfaction or conversion rates.

  • SEO Benefits: Google's ranking systems use Core Web Vitals, but good metrics do not guarantee a top position. Relevance and useful content still matter. Google's page-experience guidance explains these limits.

  • First Impressions Count: In the digital world, your website is often the first point of interaction with potential customers. A site that loads quickly and functions smoothly leaves a positive first impression, encouraging visitors to engage further with your content.

How to Improve Your Scores

Improving Core Web Vitals involves investigating three areas:

  • Largest Contentful Paint (LCP): This measures loading performance. Identify the element responsible for LCP, then investigate server response, resource discovery and delivery, and rendering delays. Preserve useful content while reducing unnecessary work.

  • Interaction to Next Paint (INP): This measures responsiveness across interactions during a visit. Investigate long main-thread tasks, expensive event handlers and rendering work. INP replaced First Input Delay (FID), which measured only the delay before processing the first interaction. Read the Chrome team's transition explanation.

  • Cumulative Layout Shift (CLS): This measures visual stability. Give images and video appropriate dimensions, reserve space for dynamic content, and check common loading and interaction states for unexpected movement.

Field data describes actual visits; Core Web Vitals are assessed at the 75th percentile. Lighthouse provides controlled laboratory diagnostics that help investigate problems. One Lighthouse score does not establish field Core Web Vitals or a business outcome. A site may also have too little eligible field data to receive a public assessment.

Conclusion

Core Web Vitals give you useful evidence about parts of the visitor experience. Use that evidence to diagnose specific obstacles, then check whether the changes help people use the site. Keep performance measures, search visibility and accepted inquiries separate when evaluating the result.