free core web vitals checker

Free Core Web Vitals Checker — LCP, INP & CLS Audit

Check your site's Core Web Vitals in under 30 seconds. AuditAI evaluates LCP, INP, and CLS against Google's thresholds and generates specific fixes to improve your scores — and your Google rankings.

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LCP
< 2.5s
Largest Contentful Paint
INP
< 200ms
Interaction to Next Paint
CLS
< 0.1
Cumulative Layout Shift

What We Check

Every scan covers the full set of performance signals that affect your Core Web Vitals scores.

Loading Performance

  • ✓
    LCP (Largest Contentful Paint) — Measures how long it takes for the largest visible element to load. Target: under 2.5s
  • ✓
    TTFB (Time to First Byte) — Server response time before the browser receives any data. Target: under 800ms
  • ✓
    Render-blocking resources — CSS and JS loaded in <head> that block the First Contentful Paint
  • ✓
    Image optimisation — Uncompressed images, wrong formats (JPEG vs WebP/AVIF), missing width/height attributes

Interactivity & Stability

  • ✓
    INP (Interaction to Next Paint) — Measures response time to user interactions. Target: under 200ms
  • ✓
    CLS (Cumulative Layout Shift) — Measures unexpected visual shifts. Target: under 0.1. Caused by images without dimensions, injected ads
  • ✓
    Unminified JS/CSS — Large unminified bundles increase parse time and delay interactivity
  • ✓
    Cache-Control headers — Missing browser cache headers force full asset re-downloads on every page load

How It Works

1

Enter any URL

Works on any publicly accessible page. No Chrome extension, no tracking code, no account required.

2

AI scans performance signals

We fetch the page, analyse HTML and response headers, and check all eight performance factors that affect CWV scores.

3

Get specific fixes

Each failing check comes with a specific fix — the exact code change or configuration setting to improve your LCP, INP, or CLS.

Why Core Web Vitals Matter for Rankings

Google confirmed Core Web Vitals as a ranking signal in 2021 under the Page Experience update. Pages that pass all three thresholds get a ranking advantage over equivalent pages that fail — particularly in competitive niches.

CWV data is collected from real Chrome users (via the Chrome User Experience Report, or CrUX). This means your scores reflect actual user experience, not just lab conditions. Mobile scores are assessed separately from desktop — a site can pass on desktop and fail on mobile.

Fixing CWV issues also directly improves user experience, which reduces bounce rates and increases conversions independently of any ranking effect.

2021
Year Google made CWV a ranking factor
Mobile
CWV scores are assessed separately for mobile vs desktop
3 metrics
LCP, INP, and CLS all must pass for full benefit

Frequently Asked Questions

What are Core Web Vitals and why do they matter for SEO?+
Core Web Vitals are three metrics Google uses to measure real-world page experience: LCP (Largest Contentful Paint — loading speed), INP (Interaction to Next Paint — interactivity), and CLS (Cumulative Layout Shift — visual stability). Google has used them as a ranking factor since 2021. Pages that pass all three CWV thresholds get a ranking boost over pages that fail.
What are the passing thresholds for Core Web Vitals?+
Google's thresholds are: LCP under 2.5 seconds (good), between 2.5–4 seconds (needs improvement), over 4 seconds (poor). INP under 200ms (good), 200–500ms (needs improvement), over 500ms (poor). CLS under 0.1 (good), 0.1–0.25 (needs improvement), over 0.25 (poor). AuditAI flags any metric in the 'needs improvement' or 'poor' range.
What causes a poor LCP score?+
The most common causes of poor LCP are: large unoptimised hero images, render-blocking JavaScript or CSS loaded in the <head>, slow server response times (TTFB over 800ms), and no CDN for static assets. AuditAI's audit identifies which of these factors applies to your specific page.
What replaced FID in Core Web Vitals?+
INP (Interaction to Next Paint) replaced FID (First Input Delay) as a Core Web Vital in March 2024. Unlike FID, which only measured the first interaction, INP measures the worst interaction delay across the entire page session. Long JavaScript tasks are the primary cause of poor INP scores.
Can I fix Core Web Vitals issues without a developer?+
Some fixes are accessible without code changes — image compression, switching to a faster hosting provider, or installing a caching plugin on WordPress. Others (deferring JavaScript, fixing CLS caused by layout shifts, optimising critical rendering path) typically require developer work. AuditAI's AI fix suggestions indicate which changes require code and which don't.

Also check out

Performance Audit →SEO Audit →CWV Explained →vs GTmetrix →

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