Definition
CrUX (the Chrome UX Report) is Google's public dataset of how real Chrome users experience websites, including their Core Web Vitals.
CrUX explained
CrUX collects performance data from real browsers, from Chrome users whose settings make them eligible, across a large number of popular websites. Chrome's documentation says it is used by Google Search to inform the page experience ranking factor, and it is available through a range of Google and third-party tools.
This is field data: measurements from real visits, on real devices and networks. It differs from lab data, such as a Lighthouse test run on one simulated device. Lab tests are ideal for diagnosing problems and testing fixes before release; field data tells you what visitors actually experienced.
Because CrUX only includes pages and sites with enough eligible traffic, smaller sites may see data for the whole origin but not for individual pages, or no data at all. In that case, add your own real-user monitoring, for example with the web-vitals JavaScript library sending results to analytics.
Example
Your developer's Lighthouse test shows a fast site, but PageSpeed Insights' field data from CrUX shows poor INP on mobile. Real visitors on mid-range phones are struggling with scripts the test machine handled easily, so fixes are prioritized for them.
Why it matters
CrUX is the data Google Search uses for page experience, so it is the score your speed work ultimately needs to move.
Related service
Page Speed Optimization
We fix LCP, INP and CLS issues so pages load fast and respond quickly for real users.
Page speed and Core Web Vitals optimizationSources
- Chrome for Developers: Chrome UX Report (CrUX) (checked 30 Sep 2026)
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Related terms
- Core Web VitalsCore Web Vitals are three Google metrics for real-user experience: loading (LCP), responsiveness (INP) and visual stability (CLS).
- PageSpeed InsightsPageSpeed Insights is Google's free tool that reports a page's real-user Core Web Vitals and runs a Lighthouse lab test with suggestions for improvement.
- INP (Interaction to Next Paint)INP (Interaction to Next Paint) measures how quickly a page visibly responds to clicks, taps and key presses; 200 milliseconds or less is good.
- LCP (Largest Contentful Paint)LCP (Largest Contentful Paint) measures how long the largest image, video or text block in view takes to render; 2.5 seconds or less is good.