Core Web Vitals: LCP, INP, and CLS in Plain Terms — 2026 Targets

Core Web Vitals quantify real user experience rather than lab theory. They are measured from actual Chrome users via the field dataset, which makes them a more honest signal than synthetic lab scores — though lab tools are still useful for diagnosis.

Largest Contentful Paint

LCP is the time from navigation to when the largest element in the viewport renders — usually a hero image or heading. Reduce it by lowering server response time, preloading the hero, using modern image formats, and removing render-blocking scripts.

Interaction to Next Paint

INP measures the delay between a user interaction and the next visual update, taking the worst interaction across the visit. Reduce it by trimming JavaScript execution time, breaking long tasks, and deferring non-critical scripts.

Cumulative Layout Shift

CLS measures unexpected layout movement. Set explicit width and height on images and media, reserve space for ads and embeds, and avoid injecting DOM elements that shift existing content.