Free Website Speed Checker
Live Lighthouse audit. Real scores. No sign-up.
Drop in any URL and we'll run the same Lighthouse audit Google uses for Core Web Vitals ranking signals — powered by the official PageSpeed Insights API. You get the performance, accessibility, best-practices, and SEO scores plus the three Core Web Vitals metrics (LCP, INP, CLS) within ~20 seconds.
No email required. No paywall. No sign-up. Just paste a URL.
Running Lighthouse audit on Google's servers… this takes 15-30 seconds.
Results for
Tested on · Lighthouse score
Category scores
Core Web Vitals
Top opportunities (fix these first)
→ Want this fixed for you? See our website speed optimization service.
How to read the scores
- 90-100 (green) — Excellent. Keep doing what you're doing.
- 50-89 (amber) — Needs work. Common; fixable in 1-3 weeks of focused effort.
- 0-49 (red) — Poor. Likely costing you traffic and conversions.
Core Web Vitals thresholds (mobile field data)
- LCP < 2.5s = good, 2.5-4.0s = needs improvement, > 4.0s = poor
- INP < 200ms = good, 200-500ms = needs improvement, > 500ms = poor
- CLS < 0.1 = good, 0.1-0.25 = needs improvement, > 0.25 = poor
Frequently asked questions
Where do the scores come from?
Google PageSpeed Insights API, which runs the open-source Lighthouse audit on a Google server in real time. Same engine as the Lighthouse panel in Chrome DevTools and the official PageSpeed Insights site at pagespeed.web.dev.
Why are mobile scores worse than desktop?
Mobile is tested on a simulated slower CPU and 3G-equivalent connection. It's harder to score well on mobile, and Google's mobile-first indexing means mobile is what counts for ranking. Optimise for mobile first.
What do the Core Web Vitals mean?
LCP (Largest Contentful Paint) is how fast the biggest visible element loads. INP (Interaction to Next Paint) is how fast the page responds to clicks/taps. CLS (Cumulative Layout Shift) is how much the page jumps around as it loads. Google ranks all three.
My score is bad. What's the most important thing to fix first?
Usually one of three things: (1) images too large — convert to WebP/AVIF, add srcset, lazy-load below the fold. (2) Third-party scripts (chat widgets, marketing tags) blocking the main thread — defer or remove. (3) CSS or JS bundles too large — bundle-split, lazy-import, code-split.
Will the score actually affect my Google ranking?
Yes — Core Web Vitals are a confirmed ranking signal since 2021, with INP added in 2024. They're not the biggest signal (content quality matters more), but they're a tiebreaker that matters in competitive niches.
Can you fix this for me?
Yes — that's exactly the service at /website-speed-optimization-cambridge. Typical engagement: audit and remediation takes 1-3 weeks, fixed-price £650-£6,500 depending on site complexity. Get measurable before/after scores.
Other free tools
Want the issues fixed, not just measured?
The tool tells you what's wrong. We fix it — fixed-price, no agency markup. Start with a 30-minute call.