Core Web Vitals
Core Web Vitals are a set of performance metrics defined by Google to measure real-world user experience on websites. Introduced as part of the Page Experience update, they became an official ranking factor in 2021.
The Core Web Vitals include:
- Largest Contentful Paint (LCP): Measures loading performance – when the main content is visible.
- First Input Delay (FID) (soon replaced by INP): Measures interactivity – how fast a page responds to user input.
- Cumulative Layout Shift (CLS): Measures visual stability – how much content shifts unexpectedly during load.
Google’s recommended thresholds for a good UX:
- LCP ≤ 2.5 s
- FID/INP ≤ 200 ms
- CLS ≤ 0.1
A well-optimized Core Web Vitals score …
- enhances user experience and satisfaction,
- reduces bounce rates and increases time on site,
- positively impacts Google rankings,
- requires technical adjustments (e.g., lazy loading, font optimization, audit tools).
Note: Tools like PageSpeed Insights and Lighthouse are essential for analyzing and improving Core Web Vitals in practice.
