SEO Glossary

Core Web Vitals: The Three Metrics Google Measures for Page Experience

Core Web Vitals measure loading, stability, and responsiveness with three metrics: LCP, CLS, and INP. Learn what passes and why it matters.

5 min read
Quick Definition

Core Web Vitals are a set of three standardized metrics - LCP, CLS, and INP - that measure the real-world experience of loading and interacting with a page.

The Three Core Web Vitals

  • LCP (Largest Contentful Paint): how quickly the largest element loads. Learn more.
  • CLS (Cumulative Layout Shift): how much the page moves while it loads. Learn more.
  • INP (Interaction to Next Paint): how quickly the page reacts to input. Learn more.

The Good Thresholds

  • LCP: 2.5 seconds or less.
  • CLS: 0.1 or less.
  • INP: 200 milliseconds or less.

Google evaluates each at the 75th percentile of real sessions, so most visits should pass.

Why They Matter for SEO

Core Web Vitals are part of Google's Page Experience signal. They are a small ranking factor, but a fast, stable site also tends to win more engagement and conversions.

How to Measure Them

  • PageSpeed Insights for lab and field data.
  • The Core Web Vitals report in Google Search Console.
  • The Performance panel in Chrome DevTools.
  • The web-vitals JavaScript library for your own analytics.

How to Improve Them

  • Fix LCP by compressing hero images and preloading key assets.
  • Fix CLS by reserving space for images and ads.
  • Fix INP by trimming long main-thread tasks and heavy JavaScript.
Example in Practice

The change: a blog with a large hero image and shifting ads.

The setup: the image is compressed and preloaded; ads get reserved slots.

The reading: LCP drops under 2.5 seconds and CLS stays under 0.1.

Why it works: the page now passes all three Core Web Vitals for most users.

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Quick Tip

Start with the biggest offender. Fix the slowest LCP, then the biggest CLS source, then the longest tasks, and most sites pass.

Frequently Asked Questions

Yes. They remain a lightweight ranking signal within Google Page Experience.
INP replaced First Input Delay in 2024 because it measures the full interaction, not just the first delay.
Each is assessed separately, and it is common to pass on desktop but fail on mobile. Optimize mobile first.
Less than content and links. They matter most when pages are otherwise similar.

Core Web Vitals, Bottom Line

Core Web Vitals translate "does the site feel fast?" into three measurable metrics.

Hit the good thresholds for most users and the experience, and often the rankings, improve.

Related Terms

The three numbers behind page speed

LCP→

Loading performance for the largest element.
CLS→

Visual stability of the page.
INP→

How quickly the page reacts to input.
Page Experience→

Google's broader set of user-experience signals.
Browse the full glossary →