Core Web Vitals are Google's user-experience metrics for the web: how fast a page loads, how quickly it becomes interactive, and how visually stable it is. They're a confirmed ranking signal — and a direct driver of bounce rate and conversions.
The three metrics that matter
- LCP (Largest Contentful Paint): how fast the main content renders. Target under 2.5 seconds.
- INP (Interaction to Next Paint): how responsive the page is to input. Target under 200ms.
- CLS (Cumulative Layout Shift): how much the layout jumps as it loads. Target under 0.1.
Where most sites leak speed
The usual suspects: render-blocking JavaScript, unoptimized images, web fonts that flash or block, and third-party tags that pile up. Fix images first — modern formats, responsive sizes, and lazy loading give the biggest LCP wins for the least effort.
A fast site isn't just better for SEO. It's better for every person who visits.
Measure, then optimize
Use field data (Chrome UX Report, PageSpeed Insights) to see what real users experience, and lab data (Lighthouse) to diagnose. Field data decides your rankings — lab data tells you what to fix.