# Chrome UX Report (CrUX)

> CrUX is a public dataset of real-user performance from Chrome, reported at the 75th percentile over a rolling 28-day window.

The **Chrome UX Report (CrUX)** is a public dataset of how real Chrome users experience websites. It reports [Core Web Vitals](/glossary/core-web-vitals) and other metrics, such as [TTFB](/glossary/ttfb) and [FCP](/glossary/fcp), for pages and origins that have enough traffic, aggregated over a rolling 28-day window.

## Lab data vs field data

Lighthouse is a **lab** test: one simulated device and network, run on demand. CrUX is **field** data from real visitors on real devices and networks. Lab data tells you what to fix and lets you test a change immediately. Field data tells you whether real visitors are having a good experience, and it is the data used to assess Core Web Vitals.

## How CrUX reports results

CrUX reports the 75th percentile. A page passes Core Web Vitals when LCP, INP and CLS are all rated good at the 75th percentile. Pages without enough traffic have no page-level data; the origin (the whole site) may still have data.

AiroPages shows 75th percentile LCP, INP and CLS from CrUX next to lab scores where data exists.