What does this Core Web Vitals report show?
Type a domain or one URL, pick mobile or desktop, and the report pulls 25 weeks of field data from Google's CrUX History API. You get a weekly chart for LCP, INP and CLS, plus TTFB and FCP. Your LCP can never be faster than either of them. It works for any site with enough Chrome traffic, a competitor's too.
Under the loading charts the LCP is split into its four parts. Further down you find CLS and INP over time, then devices and navigation types. Those last two, and the image or text share of the LCP, are for all devices together, whichever toggle you picked.
How to read the weekly CrUX charts
One bar is one week. Hover over it for the p75 of that week and the share of good, needs improvement and poor page loads.
The p75 is the number Google judges you on: three out of four page loads were at least this good.
- LCP is good up to 2.5 s and poor above 4 s
- INP is good up to 200 ms and poor above 500 ms
- CLS is good up to 0.1 and poor above 0.25
You pass the Core Web Vitals when all three are good at p75.
The badge on each metric card is the direction of a straight line drawn through all the weeks. The summary at the top compares the average p75 of the older half of the weeks with the newer half. The UX happiness score next to it is my own number: the share of good page loads in the latest week, averaged over LCP, INP, CLS, FCP and TTFB. Google doesn't use it, and there is no official Core Web Vitals score anyway.
Where does the CrUX data come from?
From Chrome on Android and desktop, for users who sync their history and share usage statistics with Google. Chrome on iPhone isn't in it. Neither is Edge.
Each weekly point covers the 28 days before it, so the points overlap. A fix that goes live on a Tuesday takes about four points to show in full.
Google adds a new point every Monday with data up to the Saturday before, so on Monday the newest point is two days old. The 28 days are how wide each window is, which is why the 28-day delay is a myth.
This is what visitors got on their own devices. PageSpeed Insights runs Lighthouse once, from a Google server, with a slow phone and network simulated. Lighthouse never clicks anything, so it has no INP at all. A 98 in Lighthouse and a red INP line here can both be true.
How is this different from the Core Web Vitals report in Search Console?
Search Console reads the same CrUX data, for your own sites only. It groups URLs that behave alike and labels each group by its worst metric over the last 28 days.
Search Console tells you which group of pages fails. The weekly bars here help you find the week it started, and from there the release.
What to check when a metric gets worse
Stay on mobile first (the report opens there): it is almost always the worse of the two. Then look at the shape of the line.
A deploy shows as a climb over about four weeks that then levels off: a new theme, a tag added in Tag Manager, a hero image that got loading="lazy". Look up what went live in the week the climb starts.
A line that keeps creeping up for months is usually third-party scripts piling up.
For LCP, open the breakdown chart and see which part grew. It only counts page loads where the LCP element is an image. More TTFB points at the server or the cache. A longer load delay means the browser finds the LCP image late. A longer load duration is a heavier image or a slow connection to where it is hosted. Growing render delay is CSS or JavaScript holding back the paint.
What CrUX history can't tell you
Small sites get no data. Google needs a lot of Chrome visits and won't say how many. Pages with a noindex or a status other than 200 are left out too. Is your URL empty? Try the whole domain. The report tries with and without www for you.
Even with data, you get one p75 per metric per week for the whole domain or one popular URL. CrUX doesn't say which template is slow, which element moves or which script holds up the click.
That takes real user monitoring on your own site. I built CoreDash for it: the page loads on your own site, with the LCP element and the slow interaction attached, so you see a fix work within hours.
