Core Web Vitals checker

What it does

Enter your field data and see at once how it compares with the Core Web Vitals thresholds Google uses for Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift. First Contentful Paint and Time to First Byte are included as diagnostics. Each metric is rated good, needs improvement or poor, and the page passes only if all three core metrics are good. For anything that misses, the checker lists where to start fixing it. The thresholds are stored in the page and were last checked in October 2026.

How to use it

1. Open PageSpeed Insights, or the Core Web Vitals report in Search Console, for your page.
2. Copy the 75th percentile field values for LCP, INP and CLS. Use lab values only when no field data exists.
3. Add FCP and TTFB if you have them; they help explain a slow LCP.
4. Read the assessment and the table, then work through the suggestions under "Where to start".

How to read the result

The assessment at the top reads Passed only when LCP, INP and CLS are all in the good range. Below it, each core metric is coloured green, amber or red, and the table shows the three bands for every metric.

Take a page with an LCP of 3.1 seconds, an INP of 180 milliseconds and a CLS of 0.08. INP and CLS are good, but LCP sits between 2.5 and 4 seconds, so it needs improvement and the page fails overall. The fix list points at the hero image and render-blocking files. Cutting LCP by 0.6 seconds would turn the whole assessment green, so that is where the effort should go.

FCP and TTFB are not part of the pass or fail. They are clues. A TTFB of 1.5 seconds uses up more than half of the 2.5-second LCP budget before the browser has any HTML, so start with the server or caching.

Images are the usual cause of a slow LCP, and the image compressor is a quick first step. Finding and fixing Core Web Vitals problems on real sites is a large part of our technical SEO service.