# Speed test (field CWV)

_Source: https://seomatrix.ai/tools/speed-test/_

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## What it does

A website speed test measures how fast and stable your pages feel to real visitors, using field data from Google's Chrome User Experience Report (CrUX) instead of a single lab run. It reports the three Core Web Vitals — LCP, INP and CLS — each with Google's own good/needs-improvement/poor verdict. This matters because Core Web Vitals are a confirmed Google ranking signal, and fast, stable pages give real users a better experience.

## What it checks

- **LCP (Largest Contentful Paint)** — The time until the largest visible element — usually a hero image or headline — finishes rendering; Google rates it good at 2.5 seconds or less at the 75th percentile.
- **INP (Interaction to Next Paint)** — How quickly the page responds to taps, clicks and keypresses across the whole visit; it replaced FID in March 2024 and is good at 200 ms or less.
- **CLS (Cumulative Layout Shift)** — The amount of unexpected content movement as the page loads; a good score is 0.1 or lower, meaning buttons and text don't jump under the user's finger.
- **Field data (CrUX)** — Real measurements from opted-in Chrome users over a rolling 28-day window, so the score reflects actual devices and networks rather than one idealized lab test.
- **75th percentile** — Google grades each metric by the experience of the slowest quarter of visits, so a page passes only when most real users, including those on weaker connections, get a good result.
- **Good / needs-improvement / poor verdict** — Google's own three-band classification per metric — the same thresholds Search Console and the page-experience signal use to judge your URLs.

## How to use it

1. Paste your page URL and run the test to pull its live CrUX field data.
2. Review each Core Web Vital — LCP, INP and CLS — against Google's good/poor verdict to see which one is failing.
3. Fix the weakest metric first (compress the LCP image, defer heavy scripts hurting INP, or reserve space for images to stop CLS), then re-test.

## FAQ

### What's the difference between field data and a lab speed test?

Field data comes from real Chrome users on their own devices and networks, aggregated by Google in the CrUX dataset, whereas a lab test is a single simulated run on one machine. Google uses field data for its ranking signal, which is why this test reports it.

### Why does my page show 'not enough data'?

CrUX only reports a URL once it has enough real Chrome traffic in the last 28 days, so low-traffic or new pages fall back to origin-level data or show none. In that case, test a higher-traffic page or your homepage.

### Do Core Web Vitals actually affect Google rankings?

Yes. Core Web Vitals are part of Google's confirmed page-experience ranking signals; they rarely outweigh strong content but act as a tie-breaker and improve crawlability and user retention.

### What counts as good LCP, INP and CLS?

Google's 'good' thresholds are LCP at 2.5 seconds or less, INP at 200 milliseconds or less, and CLS at 0.1 or less, all measured at the 75th percentile of real visits.