---
title: "How to use the free Core Web Vitals checker — Lemwatch Help"
description: "Measure LCP, INP, and CLS for any URL using real Chrome data — no PageSpeed configuration required."
canonical: "https://lemwatch.com/help/using-the-free-core-web-vitals-checker"
source: "https://lemwatch.com"
---

# How to use the free Core Web Vitals checker

> Measure LCP, INP, and CLS for any URL using real Chrome data — no PageSpeed configuration required.

## Quick answer

 Enter a URL at /tools/core-web-vitals-checker to see LCP, INP, and CLS scored against Google's thresholds — plus the biggest offender element for each metric.

## What it checks

- Largest Contentful Paint (LCP) — target under 2.5s

- Interaction to Next Paint (INP) — target under 200ms

- Cumulative Layout Shift (CLS) — target under 0.1

- Field data (real Chrome users) when available

- Lab data fallback via Lighthouse when field data is thin

## Where to find it in Lemwatch

 **/tools/core-web-vitals-checker** — public. Signed-in users can add the URL to continuous Core Web Vitals monitoring.

## How to use it

- Paste the page URL you want to measure.

- Pick mobile or desktop.

- Click Measure .

- Read the per-metric verdict and the offending element.

- Enable monitoring to catch regressions inside Lemwatch.

## FAQ

### Why does the score differ from PageSpeed Insights?

 Same CrUX data source — small differences come from time-window rounding. Trends match.

### What if the URL has no field data?

 The tool falls back to lab metrics from Lighthouse and marks the result as "estimated".

## Related

- Free mobile-friendly checker

- Free website uptime checker


## Related

- [Help centre](https://lemwatch.com/help)
- [How to use the free website uptime checker](https://lemwatch.com/help/using-the-free-website-uptime-checker)
- [How to use the free broken link checker](https://lemwatch.com/help/using-the-free-broken-link-checker)
- [DNS A record change check](https://lemwatch.com/help/dns-a-record-change-check)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [How to use the free mixed content checker](https://lemwatch.com/help/using-the-free-mixed-content-checker)