Chrome UX Report (CrUX)
CrUX is Google’s public dataset of real-user performance from Chrome. It’s the field data behind PageSpeed Insights, Search Console and the Core Web Vitals ranking signal.
Where the data comes from
CrUX collects anonymised timings from Chrome users on desktop and Android who have opted in to usage statistics reporting and sync their browsing history. It doesn’t include iOS (Chrome on iOS uses Safari’s engine), other browsers, or users in incognito. Data is aggregated per URL and per origin, split by device type and, in BigQuery, by country and connection type.
Why one slow visit in four is enough to fail
Each bar is one page view’s LCP. Google takes the 75th percentile: sort all visits, and read the value three-quarters of the way along. Increase the share of slow visits (older phones, bad networks) and watch it.
Median 1.8 s p75 2.2 s Good
Up to 25% slow visits, the median and p75 both stay good. Once more than a quarter of visits are slow, p75 jumps into the slow group and the page fails, even though most visitors were fine. That’s deliberate: the percentile makes you care about the slower tail of your audience.
The 28-day window and eligibility
PageSpeed Insights and the CrUX API report a rolling 28-day window, updated daily. A URL or origin appears only once it has enough real visits to be statistically meaningful and anonymous; Google doesn’t publish the exact threshold. That’s why smaller sites often see “no field data”: Google has no Core Web Vitals data for them, which also means there’s no page experience signal to win or lose.
Ways to access CrUX
- CoreVitals / PageSpeed Insights: current 28-day p75 for a URL and its origin.
- CrUX API: the same data as JSON, free with an API key; the CrUX History API adds weekly data for the past six months or so.
- BigQuery: monthly origin-level datasets since 2017 with country and connection breakdowns.
- CrUX Vis / Looker Studio dashboards: charts of an origin’s history without writing SQL.
Check it on your own page
Field and lab numbers for mobile and desktop, in about 30 seconds.
Questions people ask
What is CrUX data?
Real-user performance measurements (LCP, INP, CLS, FCP, TTFB and more) collected from opted-in Chrome users and published by Google per URL and origin.
Why does my site have no CrUX data?
It does not yet have enough eligible Chrome visits in the last 28 days. The threshold is not published. Lab data is your best guide until it does.
How often is CrUX updated?
The API and PageSpeed Insights update daily over a rolling 28-day window. The BigQuery dataset is published monthly.