Web Performance · Glossary

Core Web Vitals

Definition

Core Web Vitals are three metrics Google uses to measure real-world page experience: LCP (loading), INP (interactivity), and CLS (visual stability). They're a confirmed ranking signal, so passing them helps both users and SEO.

In plain English

Core Web Vitals score how a page feels to a real visitor: does it load quickly, respond fast when tapped, and stay still instead of jumping around while it loads.

How it works

  1. 1LCP (Largest Contentful Paint) — how long the main content takes to load. Good: under 2.5s.
  2. 2INP (Interaction to Next Paint) — how quickly the page responds to taps and clicks. Good: under 200ms.
  3. 3CLS (Cumulative Layout Shift) — how much the page unexpectedly shifts. Good: under 0.1.
  4. 4Google measures these from real Chrome users (field data) and uses them in ranking.
Example

A store where the product image loads instantly (good LCP), the 'Add to cart' button reacts immediately (good INP), and nothing jumps as ads load (good CLS) will feel fast — and rank better.

Why it matters

Every site that wants to rank on Google should pass Core Web Vitals. They directly affect SEO and, more importantly, conversion — slow, janky pages lose buyers before they act.

Related

Core Web Vitals — FAQs

Do Core Web Vitals affect SEO?

Yes. Google has confirmed they're a ranking signal as part of page experience. They're rarely the single deciding factor, but they matter — especially in competitive niches.

How do I improve Core Web Vitals?

Optimise images, reduce JavaScript, use server rendering, reserve space for media to avoid layout shift, and host on fast infrastructure. We target 90+ scores by default.

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