Glossary · SEO & Search
Core Web Vitals
Overview
The three metrics
Core Web Vitals track three dimensions of experience. Largest Contentful Paint (LCP) measures loading—how fast the main content appears, with 2.5 seconds or less considered good. Interaction to Next Paint (INP) measures responsiveness to clicks and taps, good at 200 milliseconds or less. Cumulative Layout Shift (CLS) measures visual stability—how much the page jumps around—good at 0.1 or less.
Field data vs lab data
Google judges the vitals using field data: real-world measurements from Chrome users, reported at the 75th percentile and visible in Google Search Console. Lab tools like Lighthouse and PageSpeed Insights simulate a single load and are useful for debugging, but only field data feeds rankings. INP replaced First Input Delay as a Core Web Vital in March 2024.
How teams improve the vitals
Fixing Core Web Vitals is largely engineering work: optimizing and lazy-loading images, splitting and deferring JavaScript, rendering pages server-side or statically, reducing main-thread blocking, and reserving space for media so nothing shifts. On website redesigns and Next.js builds, we treat these as build requirements, then verify improvements in Lighthouse and real-user data rather than guessing.
Where we use it
Related Zen in Tech services
How our team puts Core Web Vitals to work in real projects.
FAQ
Core Web Vitals — common questions
What are good Core Web Vitals scores?
Google's thresholds are LCP of 2.5 seconds or less, INP of 200 milliseconds or less, and CLS of 0.1 or less, measured at the 75th percentile of real-user page loads.
Do Core Web Vitals affect SEO rankings?
Yes. They are a confirmed ranking signal as part of Google's page experience system, though relevance and content quality still carry more weight than page speed alone.
What replaced First Input Delay (FID)?
Interaction to Next Paint (INP) replaced FID as a Core Web Vital in March 2024. INP measures responsiveness across all interactions on a page, giving a fuller picture than FID's first-input-only measure.
Keep exploring
Related terms
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Knowledge hub
From our knowledge hub
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