Free Core Web Vitals Checker

Real user performance data from Google's Chrome UX Report (CrUX) — the same dataset Google uses as a Page Experience ranking signal. No registration required.

Enter a full URL or just a domain. If URL-level data is unavailable, origin-level data is shown.

The three Core Web Vitals — explained

LCP
Largest Contentful Paint

Measures loading performance — how long it takes for the largest visible element (image, video poster, or text block) to render.

Good ≤ 2.5s Poor > 4s
CLS
Cumulative Layout Shift

Measures visual stability — how much the page layout moves unexpectedly while loading (e.g. buttons shifting before a user clicks them).

Good ≤ 0.1 Poor > 0.25
INP
Interaction to Next Paint

Measures interactivity — the delay between a user's click, tap, or key press and the next visual update on screen. Replaced FID in 2024.

Good ≤ 200ms Poor > 500ms

Why real-user data (CrUX) beats lab tests

Google Lighthouse and PageSpeed Insights run your page in a controlled lab environment — a single device, a single network, no third-party scripts cached. The results change every time you run the test. CrUX data is different: it aggregates actual Chrome browser sessions from real visitors over a 28-day rolling window, weighted by device type and connection speed.

When Google evaluates your Page Experience ranking signal, it uses CrUX — not Lighthouse. A page that gets a 90 score in Lighthouse can still fail Core Web Vitals in Google Search Console if real users on slow 4G connections experience high LCP. Our checker shows you the same field data Google uses, so there are no surprises.

Additional metrics we show

FCP — First Contentful Paint

Time until the first text or image is visible. Good: ≤ 1.8s. A high FCP indicates slow server response or render-blocking resources.

TTFB — Time to First Byte

Server response time before the browser receives the first byte. Good: ≤ 0.8s. Directly reflects hosting performance, CDN effectiveness, and server-side processing time.

Frequently asked questions

CrUX (Chrome User Experience Report) is an opt-in dataset collected by the Chrome browser from real users who have chosen to share usage statistics with Google. It aggregates page load performance over a rolling 28-day window, broken down by device type (phone vs desktop) and effective connection type. Google publishes this data via its CrUX API and uses it to determine Core Web Vitals status in Google Search Console and the Page Experience signal.

CrUX only includes a URL in its dataset if it receives enough real Chrome user sessions to meet a minimum privacy threshold (roughly a few thousand sessions per 28 days). Low-traffic URLs — even on high-traffic domains — often lack URL-level data. In that case, we automatically fall back to origin-level data (your entire domain), which gives a broader but still useful picture of performance.

Yes — Core Web Vitals are part of Google's Page Experience signal, which has been a ranking factor since 2021. Google uses a page's CrUX p75 values to determine whether it passes or fails each metric. Pages that pass all three Core Web Vitals (LCP, CLS, INP) receive a Page Experience ranking boost and are eligible to appear in certain Google Search features. However, content quality and relevance remain the dominant ranking factors — excellent Core Web Vitals won't rank a page for irrelevant queries, but poor scores can hold back a page that should otherwise rank well.

LCP is most often caused by a slow server (high TTFB), a large unoptimised hero image, or render-blocking CSS and JavaScript. Start by checking TTFB — if it's above 0.8s, focus on server performance or CDN configuration first. Then optimise the LCP element itself: serve images in WebP or AVIF format, add fetchpriority="high" to the LCP image, and ensure it is not lazy-loaded. Eliminating render-blocking scripts and using a CDN for static assets typically brings the biggest gains.

Both use the same CrUX dataset, but Search Console groups URLs into cohorts and reports the p75 across the group, while the CrUX API can return individual URL-level p75 values. Additionally, Search Console's Core Web Vitals report categorises pages based on whether 75% of sessions in the cohort pass — a stricter interpretation than a single URL's p75. The values will be close but may not match exactly.

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