🏎️ PageSpeed Checker

Lab data vs. real-user data

Lab data comes from one test run that Google does right now, on a simulated mid-range phone with a slow connection (or a desktop). It is the same every time you run it under the same conditions, so it is good for checking whether a fix helped.

Real-user data (Core Web Vitals) comes from the Chrome User Experience Report: what actual Chrome visitors experienced over the last 28 days. This is what Google uses in ranking. Small or new pages often have none - then Google shows the numbers for the whole site, or nothing.

The Core Web Vitals and their limits

• Largest Contentful Paint (LCP) - when the main content has loaded. Good: 2.5 seconds or less.
• Interaction to Next Paint (INP) - how fast the page reacts to taps and clicks. Good: 200 milliseconds or less.
• Cumulative Layout Shift (CLS) - how much things jump around while loading. Good: 0.1 or less.

A page passes when at least 75% of visits are "good" on all three.

Privacy

The address you enter is sent to Google's PageSpeed Insights service through our small server, which holds the access key. Nothing is stored. Only public pages can be tested - Google has to be able to open them.