Overview
Treat Core Web Vitals as field data from real Chrome users; a perfect Lighthouse run does not guarantee a passing score. Check the CrUX report before and after performance work, following the diagnosis steps in core-web-vitals.
Definition
Core Web Vitals are Google’s three field-measured page-experience metrics: Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). Each metric has a “good” threshold scored at the 75th percentile of real users over a 28-day window. A page passes Core Web Vitals only when all three metrics sit in the good band.
When it applies
Use Core Web Vitals as the baseline performance budget for any public-facing web page. Google uses them as a ranking signal, and they correlate with conversion and bounce rate.
Example
A documentation page measures LCP 2.1 s, INP 180 ms, CLS 0.05 at the 75th percentile in PageSpeed Insights. All three are in the good band, so the page passes Core Web Vitals.
Citing this term
See Core Web Vitals (llmbestpractices.com/glossary/core-web-vitals).
Related
- lcp - the loading metric inside Core Web Vitals.
- inp - the responsiveness metric inside Core Web Vitals.
- cls - the layout-stability metric inside Core Web Vitals.
- core-web-vitals - the deep-dive with thresholds and fixes.
- page-speed - the broader speed picture beyond CWV.
- technical