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In short: A website speed test takes 5 minutes: open PageSpeed Insights, enter the page address and look at the mobile result first. The key numbers are the three Core Web Vitals: LCP up to 2.5 s, INP up to 200 ms and CLS up to 0.1. A score of 90–100 is good, but it varies from run to run, so test 3 times and compare the median. Google ranks on real-visitor data, not on the score of one lab test.
Website speed affects both your Google rankings and whether a visitor stays or leaves for a competitor. The good news: you can check speed for free and without a developer. This guide shows how to run a website speed test, how to read the results and why the same page sometimes scores 86 and sometimes 97. For why speed matters for SEO, read website speed and SEO.
Which tool should you use for a website speed test?
There are many free tools, but most business owners need just two: PageSpeed Insights for a quick check of one page and Google Search Console for the whole site.
| Tool | By | What it shows | Best for |
|---|---|---|---|
| PageSpeed Insights | Lab and field data, recommendations | Quick check of one page | |
| Search Console → Core Web Vitals | Real-visitor data for the whole site | Status of all pages and issues | |
| Lighthouse (Chrome DevTools) | Lab test on your own computer | Developers, before and after a change | |
| WebPageTest | Catchpoint | Detailed loading waterfall, choice of location | Hunting complex problems |
| IT Solutions website audit | IT Solutions | Speed + SEO + security in one go | The big picture for owners |
Website speed test step by step
- Open pagespeed.web.dev and enter the full page address including https.
- Test several pages: the home page, your most important service or product page and a blog post. The home page is often the fastest, but visitors from Google frequently land straight on inner pages.
- Look at the mobile result first. Google indexes sites by their mobile version, and most visitors in Estonia come from phones.
- Read the top block “Discover what your real users are experiencing”. That is field data from real visitors. If there is none, the page has too few visits and you rely on the lab test.
- Check the score and the five metrics (FCP, LCP, TBT, CLS, Speed Index).
- Repeat the test 3 times and take the middle result. One run is not reliable.
- Open “Diagnostics”: it lists the actual files and images slowing the page down.
What is a good website speed test result?
Google’s Core Web Vitals measure three things: how fast the main content appears, how fast the page reacts to a click and whether content jumps while loading. The thresholds apply to the 75th percentile, so 3 out of 4 visitors must get at least that experience.
| Metric | What it measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | When the largest image or text block appears | up to 2.5 s | 2.5–4 s | over 4 s |
| INP (Interaction to Next Paint) | Response to clicks and taps | up to 200 ms | 200–500 ms | over 500 ms |
| CLS (Cumulative Layout Shift) | Content jumping while loading | up to 0.1 | 0.1–0.25 | over 0.25 |
INP replaced the older FID metric in March 2024. If an older guide talks about FID, that part is out of date.
The PageSpeed Insights score from 0 to 100 is calculated from five lab metrics with different weights:
| Metric | Weight in score | What it means |
|---|---|---|
| Total Blocking Time (TBT) | 30% | How long JavaScript blocks the page |
| Largest Contentful Paint (LCP) | 25% | Main content appearing |
| Cumulative Layout Shift (CLS) | 25% | Content shifting |
| First Contentful Paint (FCP) | 10% | First content appearing |
| Speed Index | 10% | How quickly the visible area fills in |
A score of 90–100 is green (good), 50–89 orange (needs improvement) and 0–49 red (slow).
What is the difference between field data and lab data?
- Field data comes from the Chrome User Experience Report (CrUX): real visitors, real phones and networks over the last 28 days. This is the data Google uses for ranking.
- Lab data is one simulated load on a slow phone over a slow mobile network. It is good for finding problems and comparing changes.
Small business sites often have no field data because Google does not collect enough visits. That is normal. Then use the lab test and the Core Web Vitals report in Search Console, which groups similar pages together.
Why does a website speed test give a different result every time?
The same page can score 86 and then 97 in a row. That is not a bug but the natural variance of a lab test. The reasons:
- Cache: if the page cache was just cleared, the server rebuilds the page and responds more slowly.
- Third-party scripts: live chat, ad pixels, maps, YouTube or a “not a robot” check take a different time to load each run.
- Network and test servers: Google’s test machines carry different loads.
Our own example: in November 2026 the itsolutions.ee home page scored 86–97 on mobile. The cause: six Cloudflare Turnstile checks (form protection) started at once on page load and made up about 3.4 MB of the page’s 3.7 MB. We changed it so each form’s check starts only when the visitor gets close to the form. Page weight dropped to about 400 KB and Google’s test now shows 97. Lesson: if your score jumps around a lot, look for third-party scripts.
Rule of thumb: run the test 3–5 times, compare the median and test once the page is in the cache.
What should you do after a website speed test?
Fix first what has the largest weight in the score and affects real visitors:
- LCP: optimise the first large image (WebP or AVIF, right size), do not lazy-load it and preload it.
- TBT and INP: remove unnecessary plugins and scripts, delay chats and pixels.
- CLS: give images a width and height, reserve space for ads and the cookie banner.
- Server response: page caching, a current PHP version and decent hosting.
The most common causes and fixes are in why is my website slow: 10 causes. If you want us to fix the speed for you, see WordPress speed optimisation.
How often should you check website speed?
- after every major change: a new plugin, theme, page builder or chat widget;
- once a month as part of monthly website maintenance;
- when Search Console sends a Core Web Vitals issue notice.
Frequently asked questions
Does the PageSpeed Insights score affect Google rankings?
Not directly. Google uses real-visitor Core Web Vitals data, and that is one of many signals. Relevant content matters more, but between similar pages the faster one wins, and speed also affects sales.
What is a good website speed test result?
A mobile score of 90 or more and all three Core Web Vitals green: LCP up to 2.5 s, INP up to 200 ms and CLS up to 0.1.
Why is the mobile result much worse than desktop?
The mobile test simulates a slow phone on a slow mobile network. It is strict on purpose, because many visitors use mid-range phones.
Why does PageSpeed Insights say there is no data?
The page has too few Chrome visitors for Google to build a field data report. Use the lab test and the Search Console report instead.
Is a website speed test free?
Yes. PageSpeed Insights, Search Console, Lighthouse and WebPageTest are free. Our website audit is free too and checks SEO and security as well as speed.
Sources
- Google – PageSpeed Insights: about the report (lab and field data)
- web.dev – Web Vitals (thresholds for LCP, INP, CLS)
- Chrome for Developers – Lighthouse performance scoring (metric weights)
- Lighthouse GitHub – Score variability
- Google Search Central – Core Web Vitals and Google Search
- web.dev – INP becomes a Core Web Vital (March 2024)
