Performance / Field Data
Core Web Vitals & INP Checker
Real users, not lab one. This reads the Chrome UX Report — the same 28-day field data Google ranks on — so it can measure INP, which no single server-side test can ever do.
Field data covers the last 28 days. Pages with little traffic got no URL-level data — the tool falls back to your whole origin and tells you so.
Lab tests cannot measure INP one
INP measures how long the page takes to respond after a real person taps or clicks. Nobody clicks during a synthetic test, so a lab tool can only anyhow guess — and INP is the Core Web Vital most sites fail. This tool reads Google's field data instead: real Chrome users, real interactions, the 75th percentile, which is the number the ranking signal actually uses.
What each metric means
LCP — Largest Contentful Paint
How long until the main content can be seen. Good is 2.5 seconds or less. Usually a server, image or render-blocking problem.
INP — Interaction to Next Paint
How long the page takes to respond after a tap or click. Good is 200 ms or less. Usually long JavaScript tasks jamming up the main thread.
CLS — Cumulative Layout Shift
How much the layout jumps around while loading. Good is 0.1 or less. Usually images or ads with no space reserved.
TTFB and FCP
Supporting diagnostics only, not Core Web Vitals themselves. A slow TTFB pushes every other metric out, and it also makes AI crawlers give up on a page.
Frequently asked questions
Why this one different from a speed test?
A speed test loads the page once, from one machine, on one connection — that is lab data. This is field data: what really happened to real Chrome users over 28 days, aggregated at the 75th percentile. Google ranks on the field data, so when the two disagree, this is the one that counts.
Why got no data for my URL?
CrUX only reports a URL once it has enough traffic to be statistically sound and stay anonymous. Most individual pages never hit that bar, so the tool falls back to origin-level data — your whole site averaged — and labels it clearly.
What is the 75th percentile ah?
It is the experience of the slowest quarter of your visitors. If your p75 INP is 300 ms, then 75% of interactions were faster than that and 25% were slower. Google uses p75 so that a fast median cannot cover up a badly broken minority.
Why I fail one metric but pass overall in another tool?
Google needs all three Core Web Vitals to be good at the same time. One poor metric already fails the assessment. This tool refuses to give any verdict at all when any of the three is missing, rather than imply a pass from half-complete data.
How is this different from your Page Speed Snapshot?
Page Speed Snapshot fetches the page from our server and measures what that one fetch saw — real TTFB, transfer size, compression, render-blocking. Instant and works for any URL, but it cannot see real users and structurally cannot measure INP. Use that one for diagnosis, this one for the verdict.