See whether your site is getting faster or slower

The test measures your homepage with Google PageSpeed, on mobile and on desktop. With a subscription we also measure your other important pages, every month again, so you see the change compared to the previous measurement.

Measure your homepage Mobile and desktop measured separately

The bar runs from 0 to 5 seconds, at the same pace for both devices. What a visitor on a phone experiences is not in your desktop score.

A lab measurement simulates. Your visitors do not.

Lighthouse loads your page on a simulated phone and a simulated desktop, and that is exactly what it is worth: a comparable measurement, every time under the same conditions. What it does not know is how slow your site felt for the people who were actually there yesterday.

That is why the scan adds in the numbers from your own visitors: what Google collected over the last 28 days, per device, including how fast your site responds to a click. The lab measurement says what is possible; those numbers say what happened.

2devices measured separately
7lab metrics per device
4Lighthouse scores per device
28days of real visitors
Step 1 of 2

Which website would you like to test for speed?

Start with your domain. We will then ask for your email address to begin the free measurement.

  • No account required
  • Mobile and desktop separately
  • Result shown in this card

Measure your homepage

Enter your domain and email address. You immediately get your score and the numbers below it.

  • Your score, right on the screenThe average of the two devices, with “Mobile 73 · Desktop 95” above it, so you see which half makes up that number.
  • Six numbers with their real valueLCP, CLS and TBT per device, with the measured value alongside: “5.8 s”, “0.001”, “40 ms”. No letter, the number itself.
  • And what followsThe other lab measurements, the numbers from your real visitors and the improvement points with their time savings belong to the full scan.

The check measures one page: the homepage of the domain you enter. It takes a bit longer than the other checks, because both devices run together.

Explore the full speed report

Move through the three parts of the report. Each choice immediately shows the measurements, visitor data and priorities you will find there.

Measurement by deviceyoursite.com
Example measurement
Mobile54 / 100
FCP 1.8 sLCP 3.4 sTBT 420 ms
Desktop92 / 100
FCP 0.7 sLCP 1.6 sTBT 90 ms
PerformanceAccessibilityBest practicesSEO

Where the time can be gained

Images in a modern format1.2 s
Remove unused JavaScript0.8 s
Render-blocking resources0.5 s
Enable text compression0.3 s
together2.8 s

Lighthouse estimates for each point how much time it saves, largest first. Added up, that is a direction, not a promise: the points overlap each other partly.

A score says how slow. This list says why.

Lighthouse does not just know that your page is slow, it also knows where the time gets stuck: images in an old format, JavaScript that is never used, files that hold back rendering. Each point comes with the time it saves according to the model, largest first.

Below that are the points of attention without a time saving: too many elements on the page, third-party scripts, cache that is too short. Together, that is the list your developer can get started with.

The scan does not fix it. It says where the issue is and roughly how much it is worth; what you do with it stays your decision.

What else determines your speed

Compress images

Making your photos lighter without uploading them

 SEO scan

Your SEO basics across all your pages.

 Security scan

Your headers, https and exposed files

Also read Why a fast website is essential for SEO and conversion

Frequently asked questions about website speed

What does the speed test measure?

Two Lighthouse lab measurements of your homepage: one on mobile and one on desktop. You see the PageSpeed score, LCP, CLS and TBT per device.

Is my entire website tested?

The full scan measures the pages you select yourself and names the slowest one alongside them. Other pages can therefore perform differently than your homepage.

What is a good PageSpeed score?

Lighthouse classifies 90 to 100 as good, 50 to 89 as needs improvement and 0 to 49 as poor. Also always look at the individual measurement values.

Why does my score change between measurements?

Server load, external scripts and small differences in test conditions can influence the result. One measurement is therefore a snapshot; the series in your account says more than one number.

What is INP, and why isn't it included in the lab measurement?

INP measures how long it takes for your site to respond to a click. A lab test does not click anywhere, so that value can only come from the data of real visitors. The report shows it there, alongside LCP, CLS, FCP and the server response time.

Do you save my speed scans?

We save full scans in your FlowCore account, so you can compare your mobile and desktop values with previous measurements.

Does a good score guarantee better rankings or more conversions?

No. Speed can contribute to a better user experience, but rankings and conversions depend on many factors.

Why do the scores for mobile and desktop differ?

The mobile test simulates a smaller screen, a slower connection and less processing power than the desktop test. As a result, the mobile score is often lower, even when both tests measure the same page.

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