CrUX
Also called: chrome ux report, field data, chrome user experience report
CrUX (Chrome User Experience Report) is Google's public dataset of real-user, field performance data collected from opted-in Chrome browsers. It powers the Core Web Vitals scores Google uses as a page experience ranking signal, reported as a 28-day rolling average at the 75th percentile.
Field data, not lab data
The distinction that matters: CrUX is field data (Real User Monitoring), gathered from actual Chrome sessions around the world, not lab data from a synthetic tool like Lighthouse. A Lighthouse run tells you how one simulated load behaved on one machine. CrUX tells you how your real visitors experienced the page, aggregated as a 28-day rolling average.
CrUX reports the three Core Web Vitals (LCP, INP, CLS) plus supporting metrics like TTFB and FCP. Google assesses each at the 75th percentile of page loads across mobile and desktop, so 75% of visits must clear the “good” bar to pass:
LCP ≤ 2.5 s INP ≤ 200 ms CLS ≤ 0.1That is a strict cutoff. One slow segment (say, mobile users on weak connections) can drag a whole origin into “needs improvement.”
Two eligibility rules decide whether you get data at all. A page must be publicly discoverable (returns 200, no noindex) and sufficiently popular (enough real visitors for a stable sample). Low-traffic URLs get no page-level record and fall back to origin-level aggregates.
You can read CrUX through the CrUX API, BigQuery, the CrUX Dashboard, PageSpeed Insights, or Search Console’s Core Web Vitals report. Because the same dataset feeds Google’s page experience ranking signal, CrUX is the closest thing to seeing your site the way Search’s ranking systems see it.
How it affects your traffic
Your CrUX numbers are the field data behind Google's page experience signal, so if your real-user LCP, INP, or CLS sit outside the good thresholds at the 75th percentile, you hand a ranking tie-breaker to faster competitors. Because CrUX only surfaces pages with enough traffic, a thin or slow template can quietly fail at origin level before any lab tool warns you. Our Technical SEO work targets those field metrics directly, fixing render-blocking resources, layout shift, and slow server response so the 28-day rolling average moves into the green.
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