Website speed test & Core Web Vitals

How to use the speed test

Enter the full URL of the page you want to check. Don't stop at the homepage: test a service page, a product page and a blog post too, because each template ships different images, scripts and, often, different problems. Choose Mobile for the view closest to how Google evaluates you (Google indexes mobile-first), then repeat on Desktop if most of your customers browse from a computer.

The test runs on Google's servers with a simulated phone CPU and network. Results usually appear within 15–40 seconds, and your last five runs stay saved in the browser so you can compare before and after a change.

What the results mean

• Lighthouse scores (0–100) are lab measurements. The performance score is a weighted blend of five metrics: Total Blocking Time (30%), Largest Contentful Paint (25%), Cumulative Layout Shift (25%), First Contentful Paint (10%) and Speed Index (10%). 90 and above is green, 50–89 is orange, below 50 is red.
• Real-user data (CrUX) comes from Chrome users who visited the page over the previous 28 days. What counts is the 75th percentile: if three out of four visits fall within the “good” threshold, the metric passes. The colored bar shows how visits split between good, needs improvement and poor.
• Opportunities are sorted by the estimated time you could save. They are lab estimates, useful for prioritizing, not a promise of a specific score.

Core Web Vitals thresholds

Metric	Good	Needs work	Poor
LCP — main content loads	≤ 2.5 s	2.5–4 s	> 4 s
INP — response to taps	≤ 200 ms	200–500 ms	> 500 ms
CLS — layout stability	≤ 0.1	0.1–0.25	> 0.25

For the full explanation with examples, read our guide to Core Web Vitals and site speed.

What to fix first

1. The hero image. It is usually the LCP element. Serve it in a modern format (AVIF or WebP) at the size it is actually displayed, without lazy loading and with high fetch priority. Our guide to image SEO, WebP and alt text covers the details.
2. Third-party scripts. Chat widgets, ad pixels and social embeds block the main thread and hurt INP. Defer them, or load them only on the pages that need them.
3. Server and caching. A slow time to first byte (TTFB) delays everything after it. Page caching, compression and a CDN fix most of it.
4. Layout stability. Reserve space for images, ads and the cookie banner so they don't push the text down while a visitor is reading.
5. Fonts. Use font-display: swap, load only the weights you need and subset the files to the characters your audience actually reads.

Common mistakes

The most frequent one is chasing a score of 100 instead of real-user experience: a site can score 95 in the lab and still fail Core Web Vitals on visitors’ phones. The second is testing a single page, once. The third is stacking three or four overlapping “optimization” plugins that conflict and break features. Speed is one part of technical SEO, next to crawling, indexing, structure and structured data; if you are building a new site, it is far cheaper to plan for it from day one, as in an SEO-optimized website build.

If the report shows problems you don't know how to solve, an SEO audit connects speed to the other factors that influence your rankings — or get in touch and we'll go through the report with you.