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Google Lighthouse Test - How to test your website

Lighthouse is an automated tool created by Google, for testing and improving the quality of webpages. You can run it against any webpage. It has audits for: performance, accessibility, best practices, SEO, and more.

Open a *web browser window in Incognito Mode using Ctrl-Shift-N (Cmd-Shift-N on a Mac) and go to the webpage you want to test. Incognito Mode ensures that the browser runs in a clean state. Remember too, that results will vary as factors (other than just the way your site is built) may affect your results. (Network speed, hardware age/type, browser version… can all have an effect on Lighthouse testing).

For more accurate results, do a few tests spread over a few minutes (or hours) to get an average. For a comprehensive view on understanding Lighthouse variability, visit this page.

When complete, clear the test and re-run it for mobile devices, and don't forget to run it a few times. (Below is a video recording of one of the Lighthouse tests on our site—how does your website perform?).
lighthouse-test-screen
Remember not to get too hung up (or obsessed:) with the performance scores. We've seen variations of up to 35% from tests carried out within 1 minute of each other! (See the link above regarding variability). You may however need to investigate further if your scores are consistanly low, or always lower than 50.

*You'll have noted in the video above that our own mobile page performance score was lower than our desktop version. This was simply a design based decision where we considered that the visual impact of an auto-playing video (and animated background) on mobiles, outweighed the slight reduction in performance. (It's all about balance–and it's OK to compromise:)

  1. Right Click in the browser window and select ‘Inspect' at the bottom of the pop-up, or press F12 if  you are using Windows, and fn F12 on MacOS.
  2. Select ‘Lighthouse' from the top menu. (If not showing, type Ctrl, Shift, P (Cmd, Shift, P on Macs) and select from the list.
  3. Chose your: Mode, Device and Category radio buttons.
  4. Click the Analyse page load button…


The 3 dots (vertical ellipsis) menu provides options for docking the console window, and other things.

*Lighthouse tests can run on Google Chrome, Microsoft Edge and Opera browsers, on Windows and MacOS. (Can also be run on Mozilla Firefox via an extension).