Core Web Vitals explained: LCP, INP and CLS
Core Web Vitals are three measurements of real visitors’ experience that Google uses as a ranking signal: loading (LCP), responsiveness (INP) and visual stability (CLS).
Why it matters
Largest Contentful Paint (LCP) is how long the main content takes to appear; good is 2.5 seconds or less. Interaction to Next Paint (INP) is how quickly the page responds to taps and clicks; good is 200 ms or less. Cumulative Layout Shift (CLS) measures how much the page jumps around; good is 0.1 or less.
Google assesses each at the 75th percentile of real Chrome users over 28 days, so fixes take a few weeks to show in the data. Lighthouse scores are a lab test that helps you find problems faster.
How to fix it
- LCP: make the main image small and fast (WebP/AVIF, right size), don’t lazy-load it, preload it if it is set in CSS, and speed up your server response.
- INP: reduce JavaScript, split long tasks, defer third-party scripts, and avoid heavy work in click and input handlers.
- CLS: set width and height on images and embeds, reserve space for ads and banners, and avoid inserting content above what people are reading.
- Re-test with PageSpeed Insights, then check the Core Web Vitals report in Google Search Console after a few weeks.
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