Core Web Vitals

Core Web Vitals is Google’s standard set of metrics for measuring the user experience of a web page. As of 2024 the three vitals are Largest Contentful Paint (loading), Interaction to Next Paint (interactivity), and Cumulative Layout Shift (visual stability). Each metric has a "good" threshold (LCP under 2.5s, INP under 200ms, CLS under 0.1) and a "poor" threshold above which Google considers the experience unacceptable.

The vitals are measured against real users via the Chrome User Experience Report, not synthetic loads. They feed into Google’s ranking signals — modestly, but consistently — and into the URL inspection tool in Search Console.

The practical advice: focus on the worst of the three first. A site with great LCP and CLS but a 600ms INP is going to feel slow to every user, no matter what the score sheet says.