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SEO Madmanby Adam Hafez
Free tool

Core Web Vitals thresholds checker

Classify an LCP, INP and CLS number against Google's published Good, Needs Improvement and Poor thresholds, and see the overall pass or fail.

Runs entirely in your browser. Nothing you enter is uploaded, logged or stored.

Enter all three metrics to see the overall assessment.

This tool does not measure a live page. Enter numbers you already have, from a source such as PageSpeed Insights or the Chrome UX Report, and it classifies them against Google's published thresholds. Google's real Core Web Vitals assessment runs over the 75th percentile of a distribution of real-user visits, not a single number, so a pass here is a classification of your input, not a substitute for that field assessment. Everything runs in your browser; nothing is sent anywhere.

Key takeaways

  • A page only passes Google's Core Web Vitals assessment when LCP, INP and CLS are all rated Good at once.
  • Google evaluates these thresholds at the 75th percentile of real user visits, not a single lab measurement.
  • The current Good thresholds are 2.5 seconds for LCP, 200 milliseconds for INP and 0.1 for CLS.
  • This tool classifies whatever number you type, so a pass here reflects your input, not a live field measurement of your site.
  • Everything runs in your browser, so no metric you enter is sent anywhere.

What it takes

  • Largest Contentful Paint, in seconds
  • Interaction to Next Paint, in milliseconds
  • Cumulative Layout Shift, a unitless score

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How to use it

  1. 1Get your numbers firstThis tool does not crawl or measure anything. Pull real numbers from PageSpeed Insights, the Chrome UX Report, or your own real-user monitoring before you use it.
  2. 2Enter LCP in secondsLargest Contentful Paint is the time until the biggest visible element renders. Type the value in seconds, such as 2.1.
  3. 3Enter INP in millisecondsInteraction to Next Paint is the responsiveness of the slowest typical interaction on the page, in milliseconds.
  4. 4Enter CLS as a scoreCumulative Layout Shift is a unitless score describing how much visible content moved unexpectedly. Lower is better.
  5. 5Read the per-metric ratingsEach metric gets its own Good, Needs Improvement or Poor badge against Google's published thresholds, shown next to the input.
  6. 6Read the overall resultThe page only passes when all three metrics are Good. A single Poor or Needs Improvement metric fails the overall assessment.

This tool classifies three numbers you already have against the thresholds Google publishes for its Core Web Vitals. It does not crawl your site or run a lab test: it is a calculator for numbers pulled from PageSpeed Insights, the Chrome UX Report, or your own monitoring.

The current thresholds

Google rates each metric into Good, Needs Improvement or Poor. Largest Contentful Paint is Good at 2.5 seconds or less and Poor above 4.0 seconds. Interaction to Next Paint is Good at 200 milliseconds or less and Poor above 500 milliseconds. Cumulative Layout Shift is Good at 0.1 or less and Poor above 0.25. Anything between the Good ceiling and the Poor floor is rated Needs Improvement. These are the thresholds documented on web.dev, and Google updates them infrequently but not never: INP replaced First Input Delay as the responsiveness metric in March 2024, so a threshold set is a snapshot, not a permanent fact.

Why one number here is not Google’s real assessment

Google’s own methodology does not rate a page on one measurement. It rates a page at the 75th percentile of a distribution of real visits, segmented across mobile and desktop, and a page only passes the overall Core Web Vitals assessment when LCP, INP and CLS are all Good at that percentile simultaneously. A single number you paste into this tool tells you where that one measurement would land against the published thresholds, which is useful for sanity-checking a lab result or a specific page load, but it is not the field assessment Search Console and CrUX report on. Treat a pass here as a threshold check, not proof that real users are getting a Good experience.

Use this tool to sanity-check numbers from a report you trust, not as a replacement for pulling real field data on the page you actually care about.

Sources

  1. 1.Largest Contentful Paint (LCP) - web.dev, Chrome teamPrimary
  2. 2.Interaction to Next Paint (INP) - web.dev, Chrome teamPrimary
  3. 3.Cumulative Layout Shift (CLS) - web.dev, Chrome teamPrimary
  4. 4.Core Web Vitals - web.dev, Chrome teamPrimary
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