What Are Core Web Vitals?
Core Web Vitals are a set of three metrics that Google uses to measure user experience on web pages. Since 2021, they have been a confirmed ranking factor. The three metrics measure loading speed, interactivity, and visual stability.
The Three Core Web Vitals
| Metric | Measures | Good | Needs Improvement | Poor |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | Loading speed — how fast the main content appears | Under 2.5s | 2.5-4.0s | Over 4.0s |
| INP (Interaction to Next Paint) | Responsiveness — how fast the page responds to clicks | Under 200ms | 200-500ms | Over 500ms |
| CLS (Cumulative Layout Shift) | Visual stability — how much the layout shifts during loading | Under 0.1 | 0.1-0.25 | Over 0.25 |
Note: INP replaced FID (First Input Delay) in March 2024 as the interactivity metric.
How to Improve LCP
- Optimise and compress your largest above-the-fold image
- Use a CDN to serve content from servers closer to users
- Remove render-blocking CSS and JavaScript (check with script loading checker)
- Preload critical resources
- Reduce server response time
How to Improve INP
- Minimise JavaScript execution time
- Break up long tasks into smaller chunks
- Use web workers for heavy computations
- Reduce the number of external scripts (check with CSS/JS file counter)
How to Improve CLS
- Always set width and height on images and videos
- Use lazy loading correctly (not on above-the-fold images)
- Avoid inserting content above existing content (e.g. cookie banners that push content down)
- Use CSS aspect-ratio or min-height for dynamic content areas
How Core Web Vitals Affect Rankings
Core Web Vitals are a tiebreaker ranking factor. If two pages have similar content quality and relevance, the one with better Core Web Vitals will rank higher. They are not powerful enough to override great content, but they matter on competitive queries where multiple pages are equally relevant.
Check your page for CLS-related issues (missing image dimensions, lazy loading) and performance indicators (script count, HTML size) with a free RankNibbler audit.
Last updated: March 2026