What is Core Web Vitals?

Also called LCP, CLS, INP.

Core Web Vitals are three measurements Google uses to judge how a page feels to a real visitor: how long the main content takes to appear, how much the layout jumps while loading, and how quickly it responds to a tap.

In more detail

Largest Contentful Paint should be under 2.5 seconds. Cumulative Layout Shift should be under 0.1. Interaction to Next Paint should be under 200 milliseconds. They are measured from real Chrome users rather than a lab test, so they reflect ordinary phones on ordinary connections rather than your laptop.

Why it matters for your site

They are a ranking signal, but the direct effect is larger: layout shift is why somebody taps the wrong button, and a slow largest paint is why half your mobile visitors leave before seeing anything. The most common single cause of both is images without declared dimensions.