Free Website Health Check

What the website health check measures

It runs a page through the same performance and best-practice audit Google uses for Core Web Vitals, on mobile and desktop, and returns a score from 0 to 100 for each plus the metrics behind it: how long the largest element takes to paint, how much the layout shifts while loading, and how quickly the page responds to the first tap.

Google ranks the mobile version of a page. Start with the mobile score.

How to read the scores

• Largest Contentful Paint under 2.5 seconds is good. Above 4 seconds it counts against you. It is almost always a large hero image or a slow server.
• Cumulative Layout Shift under 0.1 is good. Shifts come from images without width and height, fonts that swap late, and banners injected above content.
• Interaction to Next Paint under 200 ms is good. Heavy JavaScript on load is the usual cause.
• The lab score and the field data can disagree. Field data (from real Chrome users, shown in Search Console) is what ranking uses; the lab score is how you debug it.

The fixes that move the score most

• Compress and resize the hero image, and serve it in WebP or AVIF. This alone fixes most LCP problems.
• Set explicit width and height on every image and ad slot.
• Load third-party scripts (chat widgets, tag managers, embeds) after the page is interactive, or only after consent.
• Cache pages at the edge. A static or cached page answers in tens of milliseconds regardless of the server.