Definition
Core Web Vitals are Google’s page experience metrics: LCP (loading), INP (interactivity), and CLS (visual stability).
Detailed Explanation
| Metric | Measures | Good threshold |
|---|---|---|
| LCP | Largest Contentful Paint | ≤ 2.5s |
| INP | Interaction to Next Paint | ≤ 200ms |
| CLS | Cumulative Layout Shift | ≤ 0.1 |
Reported in GSC and PageSpeed Insights. Field data (CrUX) matters more than lab scores for ranking signals.
Nepal Context
Shared hosting and unoptimized hero images hurt LCP on mobile networks. Compress WebP images, lazy-load below fold, use local CDN if serving Nepal-heavy traffic.
Practical Examples
- A hotel homepage loads a 3 MB hero photo; converting it to a compressed WebP and setting its dimensions fixes both LCP and CLS.
- A booking widget that runs heavy JavaScript on every tap causes poor INP; loading it only when the user opens the form improves responsiveness.
- An ad slot without reserved space pushes the article down as it loads, raising CLS.
How to Check It
- Run the page in PageSpeed Insights and look first at the field data (“Discover what your real users are experiencing”).
- In Search Console, open Core Web Vitals to see groups of URLs that fail on mobile.
- After a fix, use Validate fix in Search Console; field data takes about 28 days to update.
Key Takeaways
- Mobile field data drives the ranking signal
- Fix LCP first — usually images or server response time
- INP replaced FID as the interactivity metric in 2024
Common Mistakes
- Chasing lab scores only, ignoring CrUX field data
- Huge unoptimized hero images on mobile
- Layout shift from late-loading ads or fonts (CLS)
