Core Web Vitals are Google's set of real-world performance metrics for loading, interactivity, and visual stability. They matter because a fast, stable site helps rankings, converts better, and is easier for both search and AI crawlers to process. The three current metrics are LCP, INP, and CLS.
The three metrics
- LCP (Largest Contentful Paint) — loading: how quickly the main content appears. Target ≤ 2.5s.
- INP (Interaction to Next Paint) — interactivity: how quickly the page responds to input. Target ≤ 200ms.
- CLS (Cumulative Layout Shift) — visual stability: how much the layout jumps. Target ≤ 0.1.
Google's web.dev guidance on Core Web Vitals defines these thresholds and how they're measured from real users.
Why they affect SEO
Page experience is a ranking signal, and more importantly, slow or unstable pages lose visitors before they convert. Performance also helps crawlers — including AI engines — process your content reliably. A technically sound site is the foundation that content and authority compound on.
Common causes of poor scores
- Large, unoptimised images (use WebP/AVIF with width and height set).
- Render-blocking scripts and heavy third-party code.
- Layout shifts from images, ads, or fonts loading without reserved space.
- Slow server response and no caching/CDN.
How to improve them
Serve responsive, modern-format images; code-split and defer non-critical JavaScript; reserve space for media to avoid shifts; use a swap font-display strategy; and cache aggressively via a CDN. Measure with PageSpeed Insights using real-user (field) data, not just lab scores.
Where this fits
Core Web Vitals engineering is part of every build in our website design & development service, and a clean technical foundation underpins our SEO engine. Get a free audit of your site's performance.
FAQs
Are Core Web Vitals a ranking factor? Yes — page experience including Core Web Vitals is a Google ranking signal, and good scores also lift conversions and crawlability.
What's a good LCP/INP/CLS? LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1, measured from real users.
Can a template hit these targets? Sometimes, but builder bloat often hurts them. A custom build gives more control over performance.