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Performance · Free Tool

Free Core Web Vitals Checker

Google uses Core Web Vitals as a ranking signal. This tool measures your Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP) against Google's thresholds — and tells you exactly what to fix.

Speed tests typically take 15–30 seconds.

What This Tool Checks

  • LCP (Largest Contentful Paint): Good < 2.5s, Needs Improvement < 4s, Poor ≥ 4s
  • CLS (Cumulative Layout Shift): Good < 0.1, Needs Improvement < 0.25, Poor ≥ 0.25
  • INP (Interaction to Next Paint): Good < 200ms, Needs Improvement < 500ms, Poor ≥ 500ms
  • FCP (First Contentful Paint) and TTFB as supporting metrics
  • Pass/fail verdict for each metric with Google's threshold comparison
  • Specific recommendations to improve failing metrics

Why This Matters for SEO

Core Web Vitals became an official Google ranking factor in 2021 and continue to influence search rankings. Pages that pass all three Core Web Vitals thresholds receive a "Page Experience" signal boost. Google measures these at the 75th percentile of real user visits — meaning 75% of your visitors must have a good experience for the page to qualify.

Want this audit running on every page of your site, every day? See PerfBee Performance Boost — Continuous Core Web Vitals monitoring with deploy comparisons and AI fix suggestions.

Frequently Asked Questions

What are Core Web Vitals?
Core Web Vitals are three page experience metrics that Google uses as ranking signals: LCP (Largest Contentful Paint) measures loading speed of the main content, CLS (Cumulative Layout Shift) measures visual stability, and INP (Interaction to Next Paint) measures responsiveness to user input. Google introduced them as ranking factors in 2021 and updated INP to replace FID in March 2024.
What are the Core Web Vitals thresholds?
Google's "Good" thresholds are: LCP under 2.5 seconds, CLS under 0.1 (unitless), and INP under 200 milliseconds. "Needs Improvement" is LCP 2.5–4s, CLS 0.1–0.25, and INP 200–500ms. "Poor" is LCP over 4 seconds, CLS over 0.25, and INP over 500ms. All three must be in the "Good" range for a page to pass.
How do Core Web Vitals affect SEO?
Core Web Vitals are a confirmed Google ranking factor, part of the "Page Experience" signals. They act as a tiebreaker when two pages have similar content quality — the page with better Core Web Vitals is more likely to rank higher. While content relevance is still the primary ranking factor, failing Core Web Vitals can prevent you from reaching top positions on competitive queries.
What causes a poor LCP score?
The most common LCP causes are: slow server response time (TTFB over 600ms), render-blocking resources (CSS/JS that delay the browser from rendering), resource load delay (LCP image not being preloaded), and slow element render time (heavy client-side JavaScript). The LCP element is usually a hero image, H1 heading, or background image.
What causes high CLS (layout shift)?
CLS is caused by elements that shift position after the page starts loading. Common culprits are: images and videos without declared dimensions (width/height attributes), ads and embeds loading asynchronously, fonts swapping after load (FOUT), and dynamically injected content. The fix is usually adding explicit dimensions to media and reserving space for dynamic content.
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Monitor Core Web Vitals across your whole site

One-page checks miss the bigger picture. PerfBee monitors CWV on every page, tracks changes over time, and alerts you to regressions before they affect your rankings. Get daily crawl reports, broken link alerts, Core Web Vitals tracking, and AI fix suggestions — across your entire site.

  • Crawl unlimited pages — daily, automatic
  • Broken link detection across your whole site
  • Core Web Vitals & Lighthouse audits per page
  • AI-powered code fix suggestions
  • White-label PDF reports for clients
  • Email alerts for new issues & downtime
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