What Are Core Web Vitals? LCP, INP and CLS Explained

In plain English

They exist because page speed used to be measured by things users do not feel. These three metrics try to measure what a person actually experiences: how long until the page looks ready, how quickly it reacts, and whether it jumps around.

The data comes from real visitors rather than a lab test, which is why your own connection is a poor guide to how the site performs.

What to know

LCP

Largest Contentful Paint: how long until the main content appears.

INP

Interaction to Next Paint: how quickly the page responds when tapped.

CLS

Cumulative Layout Shift: how much the layout moves while loading.

Field data

Measured from real Chrome users, reported in Search Console over 28 days.

Why it matters

As a ranking factor these are a tie-breaker rather than a lever. As a conversion factor they matter considerably more, because a page that feels slow or jumps under a thumb loses people before content quality is ever considered.

Common mistakes

×Chasing a perfect lab score while field data stays poor.

×Optimising speed on a page whose content is the actual problem.

×Ignoring CLS, which is usually the cheapest of the three to fix.

×Judging performance on desktop broadband.

FAQs

How much do they affect rankings?

Modestly, and mostly as a differentiator between otherwise comparable pages.

Lab or field data?

Field data is what counts. Lab tools are for diagnosis.

WRITTEN BY TARIQ SALLAM

Marketing Consultant. Entrepreneur. Content Creator.

I'm a marketing consultant, entrepreneur and content creator. I help businesses grow through practical marketing, websites, SEO, content and AI.

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