Core Web Vitals
Core Web Vitals are Google's three user-experience metrics: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness), and Cumulative Layout Shift (visual stability).
also: Core Web Vitals · LCP · INP · CLS · web vitals · CWV
LCP measures when the largest element in the viewport finishes rendering, and 'good' is under 2.5s. INP measures the delay from a user interaction to the next visual update across the whole visit, replacing the old First Input Delay in 2024, and 'good' is under 200ms. CLS measures how much the layout jumps as it loads, and 'good' is under 0.1. Google grades you at the 75th percentile of real-user data, so the bar is your slowish users, not your lab run.
They are a ranking signal, but the bigger reason to care is that they map to money: a slow LCP loses people before the page is usable, a janky INP makes the app feel broken, and a high CLS makes them tap the wrong thing. Field data from the Chrome User Experience Report (CrUX) is what counts, so a green Lighthouse score on fast office hardware can still fail in the field.
faq
Questions & answers
- What are the three Core Web Vitals?
- Largest Contentful Paint (loading, good under 2.5s), Interaction to Next Paint (responsiveness, good under 200ms), and Cumulative Layout Shift (visual stability, good under 0.1). Google measures them at the 75th percentile of real users.
- What replaced First Input Delay?
- Interaction to Next Paint (INP) became a Core Web Vital in March 2024 and replaced First Input Delay. INP is stricter: it looks at the full latency of all interactions during a visit, not just the first input's delay, so it reflects responsiveness across the whole session.
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