Security & SEO

    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.

    Updated 2026-07-10
    1 min read
    core-web-vitals
    lcp
    inp

    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#

  1. Largest Contentful Paint (LCP) — target under 2.5s
  2. Interaction to Next Paint (INP) — target under 200ms
  3. Cumulative Layout Shift (CLS) — target under 0.1
  4. Field data (real Chrome users) when available
  5. Lab data fallback via Lighthouse when field data is thin

    6. 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#

  6. Paste the page URL you want to measure.
  7. Pick mobile or desktop.
  8. Click Measure.
  9. Read the per-metric verdict and the offending element.
  10. Enable monitoring to catch regressions inside Lemwatch.

    11. 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#

  11. Free mobile-friendly checker
  12. Free website uptime checker
    13. Was this article helpful?

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