Website Speed Test

Enter a page URL above, choose a test location and a desktop or mobile device, then run the test. Calibre loads the page in Chrome from that location and returns load timings, Lighthouse audits, a render video and a log of every request. It is free, there is no sign-up, and each report stays shareable for 30 days.

One page load in Chrome under fixed network and device conditions. You get Time to First Byte, First Contentful Paint, Largest Contentful Paint, Total Blocking Time and Cumulative Layout Shift, plus Lighthouse audits for Performance, Accessibility, SEO and Best Practices. A third party report ranks the external scripts and embeds slowing the page most.

Both. The speed test is a lab test: one page load in Chrome from a location and device you choose. Fixed conditions make it the right tool for finding what is slow and confirming a fix. The report also includes field data from the Chrome User Experience Report (CrUX): what real Chrome visitors experienced over the previous 28 days, and the data behind Google’s Core Web Vitals ranking signal. CrUX only covers sites with enough Chrome traffic, so smaller and newer sites see the lab results alone.

A lab test measures one page load, and no two loads are identical. Server response, third party scripts and advertising vary moment to moment, so small differences between runs are normal. Larger differences between tools come from the setup: test location, the device and network emulated, and the Lighthouse version. Run the test a few times and compare the pattern.

Use Google’s Core Web Vitals thresholds. Largest Contentful Paint should be 2.5 seconds or less, Cumulative Layout Shift 0.1 or less, and Total Blocking Time under 200 milliseconds, the lab stand-in for Interaction to Next Paint, which needs real visitors to measure. Aim for Time to First Byte under 800 milliseconds and First Contentful Paint under 1.8 seconds. A Lighthouse Performance score of 90 or above is rated good.

Test from the location closest to most of your visitors. Distance adds latency: a page hosted in the United States is slower from Sydney than from North Virginia. Free tests run from Sydney, Frankfurt and North Virginia; paid plans add 14 more locations.

Start with whichever Core Web Vital is furthest from its threshold and the Lighthouse audits with the largest estimated savings. The request log shows which files delay the first paint, and the third party report shows which external scripts cost the most. Change one thing, retest from the same location and device, and compare.