Page Speed Analyser Mobile & Desktop, Core Web Vitals
Test any URL using the Google PageSpeed Insights API v5. Get mobile and desktop performance scores, Core Web Vitals (LCP, CLS, TBT, FCP), Accessibility, Best Practices and SEO scores — plus the top improvement opportunities ranked by impact. Free, instant, no account required.
Test Any URL — Mobile & Desktop, Core Web Vitals
Powered by the Google PageSpeed Insights API v5 (Lighthouse). Enter a URL to get performance, accessibility, best practices and SEO scores for both mobile and desktop simultaneously.
Include https://. Analyses are run by Google’s Lighthouse engine. Results typically take 5–15 seconds.
Core Web Vitals thresholds
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What This Page Speed Analyser Shows
Analyse Page Speed in 3 Steps
LazyTools vs Other Free Page Speed Tools
| Feature | LazyTools | pagespeed.web.dev | GTmetrix | WebPageTest |
|---|---|---|---|---|
| Powered by Google PSI API | ✅ Yes | ✅ Yes | ⚠ Lighthouse option | ⚠ Lighthouse option |
| Mobile + desktop simultaneously | ✅ Side by side | ⚠ One at a time | ⚠ One at a time | ⚠ Separate test |
| All 4 Lighthouse categories | ✅ Yes | ✅ Yes | ⚠ Performance only | ⚠ Performance only |
| Core Web Vitals pass/fail badges | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| No account required | ✅ Yes | ✅ Yes | ⚠ Account for history | ✅ Yes |
| No ads in results | ✅ Yes | ✅ Yes | ❌ Ads shown | ✅ Yes |
| Improvement opportunities list | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
Core Web Vitals Thresholds & Score Ranges
| Metric | Good | Needs Improvement | Poor | Ranking Signal |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | ≤ 2.5s | 2.5s – 4.0s | > 4.0s | Yes (Core Web Vital) |
| CLS (Cumulative Layout Shift) | ≤ 0.1 | 0.1 – 0.25 | > 0.25 | Yes (Core Web Vital) |
| INP (Interaction to Next Paint) | ≤ 200ms | 200 – 500ms | > 500ms | Yes (Core Web Vital) |
| TBT (Total Blocking Time) | ≤ 200ms | 200 – 600ms | > 600ms | Proxy for INP |
| FCP (First Contentful Paint) | ≤ 1.8s | 1.8s – 3.0s | > 3.0s | Indirect |
| PSI Score (0–100) | 90–100 | 50–89 | 0–49 | Indirect |
Page Speed Analysers — What the Scores Mean and How to Improve Them
What is PageSpeed Insights and what does the score mean?
Google PageSpeed Insights (PSI) is a tool that measures web page performance using the Lighthouse auditing engine. The performance score is a weighted composite of six metrics: First Contentful Paint (10%), Speed Index (10%), Largest Contentful Paint (25%), Total Blocking Time (30%), Cumulative Layout Shift (15%) and Time to Interactive (10%). The score ranges from 0 to 100. Scores of 90–100 are Good (green), 50–89 are Needs Improvement (orange), 0–49 are Poor (red).
Why mobile scores are always lower than desktop
Mobile Lighthouse tests simulate a mid-tier Android device (approximately a Moto G4) with a throttled 4G network connection (10 Mbps download, 40ms RTT) and 4x CPU throttling. Desktop tests use a fast connection with no CPU throttling. This means a resource that loads in 200ms on desktop may take over 1,000ms on the simulated mobile device. A 20–30 point gap between mobile and desktop scores is completely normal. Since Google uses mobile-first indexing, the mobile score is more important for search rankings.
Core Web Vitals and Google search rankings
Google confirmed in May 2021 that Core Web Vitals are search ranking signals. The three Core Web Vitals are: Largest Contentful Paint (LCP) measuring loading performance, Cumulative Layout Shift (CLS) measuring visual stability, and Interaction to Next Paint (INP) measuring responsiveness (INP replaced First Input Delay in March 2024). Pages with Good Core Web Vitals scores have a small but real ranking advantage over pages with Poor scores, particularly in competitive search results where other ranking factors are similar.
How to improve LCP (Largest Contentful Paint)
LCP is most commonly degraded by a large hero image or background image that loads slowly. Key fixes: use a CDN to serve images closer to users, enable HTTP/2 or HTTP/3, compress images to WebP format (typically 30–50% smaller than JPEG), set explicit width and height attributes on images to prevent layout shifts, preload the LCP image with a link rel="preload" tag, and remove render-blocking CSS or JavaScript that delays the first paint.
How to improve CLS (Cumulative Layout Shift)
CLS is caused by page elements moving unexpectedly during load. Most common causes: images without explicit width and height (browser reserves no space until image loads), ads or embeds that expand on load, web fonts causing a flash of unstyled or invisible text (FOIT/FOUT), and late-loading content injected above the fold. Fix: always set width and height on images, reserve space for ads, use font-display: optional or swap, and avoid injecting content above existing content.
How to reduce Total Blocking Time (TBT)
TBT accumulates whenever the browser main thread is blocked for more than 50ms by a long task (any task taking more than 50ms contributes the excess time to TBT). High TBT is almost always caused by too much JavaScript executing at page load. Fixes: code-split large JavaScript bundles, defer non-critical scripts with async or defer attributes, remove unused JavaScript, move third-party scripts to load after the user interaction, and use Web Workers for computationally expensive tasks.
Frequently Asked Questions
Scores of 90–100 are Good (green), 50–89 are Needs Improvement (orange), 0–49 are Poor (red). Most well-optimised websites score 80–95 on desktop and 60–80 on mobile. Mobile scores are typically 20–30 points lower due to simulated slower device and network conditions.
Yes. Core Web Vitals (LCP, CLS, INP) are confirmed ranking signals since May 2021. Pages with Good Core Web Vitals have a ranking advantage. The PageSpeed score itself is not directly a ranking signal, but the underlying metrics that compose it (LCP, CLS, INP) are.
LCP measures how long the largest visible element (usually a hero image or main heading) takes to finish rendering. Good: under 2.5 seconds. Needs Improvement: 2.5–4 seconds. Poor: over 4 seconds. LCP is a Core Web Vital and a confirmed Google ranking signal.
Mobile tests simulate a mid-tier Android device with 4G throttling (10 Mbps) and 4x CPU slowdown. Desktop tests use fast broadband with no CPU throttling. A 20–30 point gap is normal. Mobile matters more for rankings as Google uses mobile-first indexing.
The highest-impact fixes are: compress and resize images (use WebP, set width and height), defer non-critical JavaScript, eliminate render-blocking resources, use a CDN, enable browser caching, and preload your LCP image. Check the Opportunities section in the results for fixes specific to your page, ranked by estimated time saving.
Lighthouse is the auditing engine that runs the tests. PageSpeed Insights is Google's web interface and API that wraps Lighthouse and adds field data from the Chrome User Experience Report (CrUX). Both use the same Lighthouse tests. The PSI API (used by this tool) returns the same scores as running Lighthouse in Chrome DevTools under standardised throttling conditions.
This tool runs a free website speed test using the official Google PageSpeed Insights API. Enter your URL, click Analyse, and get the same scores as Google's own tool — mobile and desktop simultaneously, with Core Web Vitals and improvement opportunities. No account, no ads, instant results.
Yes — this page speed test is SEO-focused. It shows the Lighthouse SEO score alongside Performance, plus Core Web Vitals which are confirmed ranking signals. Use it to check any page before and after optimisation to measure the improvement. Free, no account, powered by Google’s own PSI API v5.