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Website Speed & Core Web Vitals Checker

Audit webpage loading performance and measure essential Core Web Vitals metrics. Inspect Largest Contentful Paint, Cumulative Layout Shift, and Interaction to Next Paint to optimize search rankings and user experience.
✓ Free✓ No signup✓ Privacy first✓ Runs in your browser
Website Speed & Core Web Vitals Checker - ToolPremier
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Enter a URL to test page load speed, inspect Google Core Web Vitals (LCP, FID/INP, CLS, FCP, TTFB), and diagnose performance bottlenecks.

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Performance Score

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LCP Good
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Largest Contentful Paint
Good ≤ 2.5s · Poor > 4.0s
INP / TBT Good
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Total Blocking Time
Good ≤ 200ms · Poor > 600ms
CLS Good
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Cumulative Layout Shift
Good ≤ 0.1 · Poor > 0.25
FCP Good
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First Contentful Paint
Good ≤ 1.8s · Poor > 3.0s
SI Good
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Speed Index
Good ≤ 3.4s · Poor > 5.8s
TTFB Good
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Time to First Byte
Good ≤ 0.8s · Poor > 1.8s
💡 Top Speed Opportunities & Diagnostics

Website Speed & Core Web Vitals Checker · 100% Client-Side Diagnostics · ToolPremier

How it works

Get it done in three steps

1. Enter the target URL

Type or paste the full website address you want to evaluate into the analysis input bar.

2. Run the speed audit

Execute the diagnostic test to query real-world and lab performance indicators across mobile and desktop viewports.

3. Review actionable recommendations

Inspect detailed breakdown scores, resource transfer sizes, and prioritized technical fixes to reduce page load latency.

FAQ

Common questions

Core Web Vitals are a collection of three specific performance benchmarks established by Google that measure real-world user experience: Largest Contentful Paint (loading), Interaction to Next Paint (interactivity), and Cumulative Layout Shift (visual stability). Search engines use these metrics as confirmed ranking signals in organic search algorithms. Websites that meet Google’s ‘Good’ thresholds provide better visitor satisfaction and often enjoy higher visibility in search results.
Lab data measures performance in a controlled synthetic environment using standardized network throttles, making it ideal for debugging specific code bottlenecks. Field data, collected from the Chrome User Experience Report, reflects actual loading times experienced by real human visitors across diverse devices and internet connections. This tool presents both perspectives so you can identify immediate coding issues while understanding genuine user experience.
Improving LCP involves speeding up the delivery and rendering of the largest visible element on the screen, which is typically a hero image or heading block. Common fixes include optimizing image file sizes with modern formats like WebP, preloading critical resources, using a content delivery network, and reducing server response times. The audit report identifies the exact element triggering LCP so you can optimize it directly.
The audit queries public performance APIs directly from your browser session without publishing your domain scores to a public leaderboard or saving them to external databases. All diagnostic data is presented strictly to you on your screen. Refreshing the browser clears the session immediately.

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About the Website Speed & Core Web Vitals Checker

The Website Speed & Core Web Vitals Checker is a diagnostic tool designed for web developers, SEO specialists, and digital site owners. It provides clear visibility into page load performance, visual rendering shifts, and responsive interactivity metrics that impact bounce rates. By translating complex technical audit data into straightforward recommendations, it empowers teams to accelerate website load times effectively.

Benefits

  • Pinpoint performance bottlenecks — identify oversized scripts, unoptimized image assets, and slow server response times dragging down speed.
  • Measure Core Web Vitals — evaluate your site against Google's LCP, CLS, and INP thresholds to safeguard search ranking eligibility.
  • Compare desktop and mobile metrics — analyze performance disparities between high-powered desktop computers and cellular mobile devices.
  • Prioritize technical fixes — review clear guidance on code minification, asset compression, and browser caching to speed up user journeys.

Privacy

All diagnostic queries are conducted through public performance endpoints within your browser, and no website addresses or audit metrics are permanently retained.