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Website Analysis

Core Web Vitals Checker (CrUX)

Look up real-user Core Web Vitals field data from the Chrome UX Report — LCP, INP, CLS, FCP and TTFB at the 75th percentile, with pass/fail assessment.

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This shows real-user (field) data from the Chrome UX Report — the same data Google uses for the page-experience signal — not a lab simulation. If a specific URL has too little traffic, switch to Origin scope. For lab diagnostics and opportunities, use the PageSpeed Insights Checker.

Core Web Vitals Checker: Real-User Field Data from the Chrome UX Report

Look up the actual Core Web Vitals your visitors experience — LCP, INP, CLS, FCP and TTFB at the 75th percentile — straight from Google's Chrome UX Report. This is field data from real Chrome users, the same source behind Google's page-experience signal, not a one-off lab test.

Field data vs lab data

Most speed tools run a single simulated load (lab data). Google ranks pages using field data: aggregated measurements from real users over the past 28 days. This checker queries that field dataset directly, so you see what Google actually sees.

  • Query a single URL, or the whole origin for site-wide coverage.
  • Split results by mobile, desktop, or all devices.
  • See the good / needs-improvement / poor distribution, not just an average.

The metrics explained

Three metrics are the Core Web Vitals; the other two provide context:

  • LCP (Largest Contentful Paint) — loading. Good is 2.5 s or less at the 75th percentile.
  • INP (Interaction to Next Paint) — responsiveness. Good is 200 ms or less. INP replaced FID in 2024.
  • CLS (Cumulative Layout Shift) — visual stability. Good is 0.10 or less.
  • FCP (First Contentful Paint) — first pixel of content. Good is 1.8 s or less.
  • TTFB (Time to First Byte) — server response. Good is 0.8 s or less.

Why the 75th percentile matters

Google assesses each metric at the 75th percentile of your users, meaning 75% of visits must hit the 'good' threshold to pass. A fast average can still fail if a quarter of your users have a slow experience, so optimizing the tail — slow devices and networks — is what moves the needle.

How to improve your scores

Once you know which metric fails, target it specifically:

  • LCP: optimize your largest image or hero, use a CDN, and preload key resources.
  • INP: reduce long JavaScript tasks and break up heavy event handlers.
  • CLS: set width and height on images/embeds and reserve space for dynamic content.
  • TTFB: improve hosting, caching, and database response times.

FAQ

Why does it say there is no data for my URL?
The Chrome UX Report only includes pages with enough real-user traffic. Low-traffic URLs return no data — switch to Origin scope to see site-wide vitals instead.
Is this the same data Google ranks with?
Yes. It comes from the Chrome UX Report, the field dataset behind Google's Core Web Vitals assessment and page-experience signal.
How fresh is the data?
CrUX reports a rolling 28-day aggregate, so changes you deploy take a few weeks to fully reflect in field data.
What is the difference between this and PageSpeed Insights?
PageSpeed Insights runs a lab test with optimization suggestions; this tool shows the real-user field data. Use both together: field data to know if you pass, lab data to know what to fix.
Did INP replace FID?
Yes. As of March 2024, Interaction to Next Paint (INP) is the official Core Web Vital for responsiveness, replacing First Input Delay (FID).

Related tools

Pro tip: pair this tool with PageSpeed Insights Checker and View Source Code for a faster SEO workflow.