Term · Search & content
Core Web Vitals
Core Web Vitals are three metrics Google uses to measure the experience of loading and using a web page, based on data from real Chrome users. They are part of Google's page experience signals.
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Explained
The three metrics
| Metric | Measures | "Good" threshold |
|---|---|---|
| LCP — Largest Contentful Paint | How fast the main content appears | 2.5 seconds or less |
| INP — Interaction to Next Paint | How fast the page responds to input | 200 milliseconds or less |
| CLS — Cumulative Layout Shift | How much the layout moves unexpectedly | 0.1 or less |
A page passes when at least 75% of visits meet the "good" threshold for each metric. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024. Source: web.dev.
Where to check
- Google Search Console — Core Web Vitals report by page group, for mobile and desktop.
- PageSpeed Insights — field data for a URL or origin, plus lab diagnostics.
Typical causes of poor scores
- LCP: large images, slow server, render-blocking scripts and fonts.
- INP: heavy JavaScript, especially third-party tags and widgets.
- CLS: images and ads without reserved space, late-loading banners and fonts.
See Core Web Vitals for business owners and website speed optimisation.
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FAQ
Frequently asked questions
Do Core Web Vitals decide rankings?
They are one of many signals; relevance and content quality matter more. Their effect on visitors' behaviour is often more noticeable.
Why is there no data for our site?
Field data requires enough real-user visits. Small sites may see only lab measurements.