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Website Speed Checker

How fast is your website, really?

Run a full Lighthouse audit on any public URL. You'll get Core Web Vitals from real visitors, lab metrics from a controlled run, and a prioritised list of what to fix first — in under a minute, free, no signup.

How it works

Two kinds of data, one report

Speed tools disagree because they measure different things. This report shows both sources side by side so you can tell a real problem from a noisy measurement.

Field data — what your visitors felt

Pulled from the Chrome UX Report: anonymised measurements from real Chrome users over the last 28 days. It's the data Google uses to assess Core Web Vitals, so it's the number that matters for search. It only exists once a page gets enough traffic.

Lab data — a controlled, repeatable run

Lighthouse loads your page in a headless Chrome on emulated hardware with a throttled network. Every run uses identical conditions, which makes it the right tool for checking whether a change actually helped.

  1. 1

    Paste a URL

    Any public page. Pick mobile or desktop — Google ranks on mobile, so start there.

  2. 2

    We run Lighthouse

    Google's servers load the page, throttle it, and score around 50 audits.

  3. 3

    Fix the top items

    Opportunities are sorted by estimated time saved. Start at the top and re-run.

Metrics

What each number actually means

Core Web Vitals come first — they're the three metrics Google uses as a ranking signal. The rest explain how you got there.

Largest Contentful Paint

LCP

How long until the biggest thing on screen — usually a hero image or headline — has rendered. This is the metric visitors experience as 'the page loaded'.

Good: under 2.5s

Interaction to Next Paint

INP

How quickly the page responds when someone taps or clicks. High INP almost always means too much JavaScript running on the main thread.

Good: under 200ms

Cumulative Layout Shift

CLS

How much the layout jumps while loading. Caused by images without dimensions, late-loading fonts, and ads injected above existing content.

Good: under 0.1

First Contentful Paint

FCP

When the first text or image appears. It tells the visitor something is happening, even if the page isn't finished.

Good: under 1.8s

Total Blocking Time

TBT

How long the main thread was blocked and unable to respond during load. It's the lab stand-in for INP, and the single best predictor of a sluggish-feeling page.

Good: under 200ms

Time to First Byte

TTFB

How long your server took to start responding. Slow TTFB delays everything after it, so fix this before optimising anything on the front end.

Good: under 800ms