INP & Core Web Vitals Checker
Test Interaction to Next Paint (INP), LCP, and CLS for any URL — with mobile and desktop breakdowns. Data comes straight from Google's Chrome UX Report, the same real-user numbers Google uses for search ranking.
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What is INP?
Interaction to Next Paint measures how long the page takes to visually respond to a user action — a click, tap, or keypress. It replaced First Input Delay (FID) as a Core Web Vital on March 12, 2024 because INP captures every interaction during the session, not just the first one. Good INP is under 200 ms at the 75th percentile; above 500 ms is Poor and counts against Google search ranking.
Also tested: LCP, CLS, TTFB, and FCP
This tool reports all three Core Web Vitals — INP, Largest Contentful Paint (LCP), and Cumulative Layout Shift (CLS) — along with Time to First Byte (TTFB) and First Contentful Paint (FCP) as supporting context. TTFB in particular compounds into every other metric: a 1.5-second TTFB already burns most of your INP budget before any user-visible work starts.
Why field data (CrUX) and not Lighthouse?
Google ranks sites based on real Chrome user data, not synthetic lab tests. The Chrome UX Report aggregates these metrics from opted-in Chrome browsers over a 28-day rolling window. Lighthouse can estimate INP in a lab run via Total Blocking Time correlation, but only field data reflects what real visitors experience and only field data drives ranking. If CrUX has no data for a URL, it usually means the site has too little Chrome traffic (a few hundred visits per month minimum).
Frequently Asked Questions
Under 200 ms at the 75th percentile of page visits over a 28-day window. Between 200 ms and 500 ms is 'needs improvement'. Above 500 ms is Poor and triggers a Core Web Vitals failure in Search Console, which can hurt search ranking.
The Chrome UX Report only publishes data for URLs or origins that have received enough Chrome traffic in the last 28 days — typically a few hundred page views at minimum. New sites, low-traffic pages, and private/staging URLs will show no data. We automatically fall back from URL-level to origin-level data before showing the no-data state.
FID (First Input Delay) measured only the very first interaction on a page. INP (Interaction to Next Paint) measures the 98th percentile of ALL interactions during the session — typing in a form, clicking buttons, scrolling, dropdown menus — and reports the worst experiences. INP is a much better proxy for how responsive the page actually feels.
Break up long JavaScript tasks, move heavy work to Web Workers, defer non-critical scripts, and avoid layout thrashing in event handlers. Our full INP fix guide at /learn/inp-interaction-to-next-paint walks through six concrete techniques with code examples.