Crawlsonar

Core Web Vitals Checker

The three metrics Google ranks on — LCP, INP and CLS— from real Chrome-user field data when available, plus the Lighthouse lab score, with a fix for whatever’s failing. Tested on mobile.

The three Core Web Vitals

  • LCP — Largest Contentful Paint (loading): good ≤ 2.5s. When the main content appears.
  • INP — Interaction to Next Paint (responsiveness): good ≤ 200ms. How quickly the page reacts to input. Replaced FID in 2024.
  • CLS — Cumulative Layout Shift (visual stability): good ≤ 0.1. How much the layout jumps as it loads.

Field vs lab data

Field data is what real Chrome users experienced over the last 28 days (CrUX) — this is what Google actually ranks on. It only exists once a page/site has enough traffic; for quieter sites we show the labresult from a single Lighthouse run instead. INP is a field-only metric, so it may read as “no data” on low-traffic pages.

Related

Frequently asked questions

▸ What are good Core Web Vitals?

LCP 2.5s or less, INP 200ms or less, and CLS 0.1 or less, measured at the 75th percentile of your real users.

▸ Why is there no field data for my site?

Field (CrUX) data only exists for pages with enough real Chrome traffic. Low-traffic sites fall back to lab (Lighthouse) data, and INP is field-only.