Test all five Core Web Vitals with lab data and real-user CrUX field data side by side. See exactly which metrics are failing and what to fix.
Why it matters
Google uses Core Web Vitals as a ranking signal. Failing metrics means lower search visibility, higher bounce rates, and lost traffic. But most tools only give you the scores — not what's causing them.
of visitors leave if a page takes more than 3 seconds to load
of pages that fail Core Web Vitals rank lower in mobile search
fewer visitors abandon pages that pass all Core Web Vitals
What you get
TTFB, FCP, LCP, TBT, and CLS — measured in a real Chrome browser with Lighthouse v12. See exactly which metrics pass and which need work.
Lab results next to real field data from Google's Chrome User Experience Report. Know how actual visitors experience your site, not just how it performs in a test.
Screenshot and details of your Largest Contentful Paint element — the exact image, text block, or video that determines your LCP score.
Actionable recommendations sorted by impact, with estimated time savings per fix. Know what to optimize first for the biggest Core Web Vitals improvement.
FAQ
Core Web Vitals are a set of metrics defined by Google that measure real-world user experience on web pages. They include Largest Contentful Paint (LCP) for loading speed, Cumulative Layout Shift (CLS) for visual stability, and Interaction to Next Paint (INP) for responsiveness. Google uses these metrics as ranking signals in search results.
Google uses Core Web Vitals as a ranking signal in search results. Pages that pass all Core Web Vitals thresholds get a ranking boost, while pages that fail may rank lower — especially on mobile. This is part of Google's broader Page Experience update.
Lab data (like Lighthouse) measures performance in a controlled environment with a simulated device and network. Field data (like CrUX) comes from real users visiting your site with their actual devices and connections. DebugUtils shows both side by side so you can see how your optimizations translate to real-world results.
Google considers these scores 'good': LCP under 2.5 seconds, CLS under 0.1, TBT under 200ms (lab proxy for INP), FCP under 1.8 seconds, and TTFB under 800ms. DebugUtils color-codes each metric green, yellow, or red based on these thresholds.
Yes. DebugUtils runs full Core Web Vitals tests for free with no signup required. You get lab metrics from Lighthouse v12 plus real-user CrUX field data, LCP element analysis, and prioritized fix recommendations — all in a shareable report URL.
How it works
Paste any URL. We handle normalization, redirects, and protocol detection.
Real Chrome browser runs Lighthouse and captures network data, screenshots, and video.
Scores, metrics, waterfall, filmstrip, video, and recommendations — ready in under 2 minutes.
Paste your URL, get a full report in under 2 minutes. No account needed.
Results are shareable via URL and stored for 90 days.