Core Web Vitals: LCP, INP, and CLS Explained for 2026
Google uses Core Web Vitals as a ranking signal. This guide explains what LCP, INP, and CLS measure, what scores are considered good, and how to improve them.
Core Web Vitals became a Google ranking factor in 2021. They measure real user experience — loading, interactivity, and visual stability. Getting them right improves both rankings and actual user satisfaction. Here's what each metric means and what scores are considered good.
LCP: Largest Contentful Paint
What it measures: How long until the largest image or text block in the viewport is rendered.
- Good: Under 2.5 seconds
- Needs improvement: 2.5–4 seconds
- Poor: Over 4 seconds
Main fix: Optimize the hero image (compress, preload, WebP format, CDN).
INP: Interaction to Next Paint (Replaced FID)
What it measures: The delay between a user interaction (click, tap, key press) and the next visual update. INP replaced First Input Delay (FID) in March 2024.
- Good: Under 200ms
- Needs improvement: 200–500ms
- Poor: Over 500ms
Main fix: Break up long JavaScript tasks, avoid main-thread blocking.
CLS: Cumulative Layout Shift
What it measures: How much the page layout unexpectedly shifts while loading. Experienced as content jumping around when images load or ads appear.
- Good: Under 0.1
- Needs improvement: 0.1–0.25
- Poor: Over 0.25
Main fix: Always set explicit width/height on images and iframes. Reserve space for ads.
How to Measure Core Web Vitals
- Google Search Console: Core Web Vitals report shows real user data (field data)
- PageSpeed Insights: Both lab and field data per URL
- Chrome DevTools: Performance panel and Lighthouse tab