Core Web Vitals: How to Measure and Optimize LCP, INP, CLS

Core Web Vitals are real-user experience metrics that Google uses as a ranking factor. The three core metrics — LCP, INP and CLS — reflect a page's loading speed, responsiveness and visual stability.

The three Core Web Vitals

LCP — Largest Contentful Paint

Measures when the largest element (usually a hero image or text block) finishes rendering. Target: under 2.5 seconds.

INP — Interaction to Next Paint

Replaced FID in 2024 and measures response latency to user interactions. Target: under 200ms.

CLS — Cumulative Layout Shift

Measures how much the layout "jumps" during load. Target: under 0.1.

Quick optimization tips

• LCP: compress and preload the hero image, use a CDN, remove render-blocking CSS/JS.
• INP: break up long JavaScript tasks, avoid running heavy scripts right after interaction.
• CLS: set width/height on images, reserve space for banners/ads, avoid injecting dynamic content above the fold.

Where to measure

Field data (real users) comes from the Chrome UX Report; lab data comes from Lighthouse or PageSpeed Insights.

Measure now: Check speed & Core Web Vitals free for any URL.

Conclusion

Improving Core Web Vitals boosts both SEO and conversion rates — faster pages retain users better. Prioritize LCP first because it's easy to improve and has the biggest impact.