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".