Core Web Vitals
Definition: Core Web Vitals are three Google metrics for real-user experience: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness and Cumulative Layout Shift for visual stability.
Also called: CWV, web vitals, page experience metrics
Updated
The three metrics and their thresholds
| Metric | What it measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| Largest Contentful Paint | Loading | 2.5 s or less | 2.5 s to 4 s | Over 4 s |
| Interaction to Next Paint | Responsiveness | 200 ms or less | 200 ms to 500 ms | Over 500 ms |
| Cumulative Layout Shift | Visual stability | 0.1 or less | 0.1 to 0.25 | Over 0.25 |
A page passes when at least 75% of real visits fall within the “good” range for all three, measured separately on mobile and desktop (web.dev). Interaction to Next Paint replaced First Input Delay as the responsiveness metric in March 2024.
Field data and lab data
Field data comes from real Chrome users, collected in the Chrome UX Report over a rolling 28-day window. It is what Google uses to assess a page, and what Search Console’s Core Web Vitals report shows. Pages with little traffic may have no field data of their own, in which case tools such as PageSpeed Insights fall back to data for the whole origin.
Lab data comes from a simulated load in a tool such as Lighthouse. It is repeatable and useful for debugging, but it cannot measure INP directly and often differs from what visitors experience.
How much they matter for rankings
Google says good Core Web Vitals align with what its core ranking systems seek to reward, and recommends achieving them for success with Search (Core Web Vitals and Google Search). It does not say how much weight they carry.
Our view: they behave more like a tiebreaker than a lever, since relevance and content quality come first. Fix Core Web Vitals for your visitors and conversions; any ranking effect is a side benefit. The Core Web Vitals checker shows field and lab data for any URL.