Free Online Core Web Vitals Check Tool

A Core Web Vitals check reports a page's LCP, INP and CLS — the three user-experience signals Google uses in ranking — from a Lighthouse run.

This tool uses AI and sends your text to a secure API for processing. No data is stored after your session.

Instant results Secure AI processing No signup needed

How to Use This Tool

Choose Mobile or Desktop before running the check.
Enter the URL of the page whose experience you want to measure.
Select Check vitals and let Lighthouse load the page.
Read the three Core Web Vitals cards (LCP, INP, CLS) against the listed thresholds.
Use the supporting timings to diagnose a failing vital — for example high TBT often hurts INP.

What Is a Core Web Vitals Check?

Core Web Vitals are the three user-centred metrics Google uses to measure page experience. Largest Contentful Paint (LCP) measures loading and should be 2.5 seconds or less. Interaction to Next Paint (INP) measures responsiveness and should be 200 milliseconds or less. Cumulative Layout Shift (CLS) measures visual stability and should be 0.1 or less. Passing all three at the 75th percentile of visits counts as a good experience.

This check loads your URL through Lighthouse and returns the three vitals plus supporting timings — First Contentful Paint, Total Blocking Time and Speed Index — so you see not just whether a page passes but why. Because the vitals describe how a page feels to a visitor rather than raw server speed, improving them tends to help rankings and conversions. As with all lab tools, mobile is throttled and usually shows weaker numbers.

The data comes from the third-party Google PageSpeed Insights API, which the site owner must configure with a key; without it the tool shows a notice. Lighthouse returns lab data from one run, so field data can differ.

Frequently Asked Questions

What are the three Core Web Vitals?

Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). Together they describe how a page feels to a real visitor.

What are the passing thresholds?

LCP should be 2.5 seconds or less, INP 200 milliseconds or less, and CLS 0.1 or less. Hitting all three at the 75th percentile is considered a good experience.

Are these lab or field numbers?

This check returns Lighthouse lab data for a single run. Real-world field data from the Chrome User Experience Report can differ, so use this as a fast diagnostic rather than the final word.

Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.

Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.

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