Core Web Vitals in 2025: What Actually Moves the Needle
Since Google introduced Core Web Vitals as a ranking signal, there's been a lot of noise about which metrics matter and how much. The data is clearer now. Here's what the research actually shows.
The Three Core Web Vitals
| Metric | Measures | Good Threshold |
|---|---|---|
| LCP (Largest Contentful Paint) | Loading speed of main content | < 2.5 seconds |
| INP (Interaction to Next Paint) | Responsiveness to user input | < 200ms |
| CLS (Cumulative Layout Shift) | Visual stability | < 0.1 |
What Correlates with Rankings
Multiple studies in 2024-2025 have found that LCP has the strongest correlation with organic ranking improvements when improved. INP matters significantly for interactive pages. CLS has the weakest direct correlation with rankings but the strongest correlation with bounce rate.
The practical implication: fix LCP first, then INP, then CLS.
Fastest Wins for LCP
1. Preload your hero image
Add a preload link tag in your HTML head for the largest above-the-fold image.
2. Use WebP format
WebP images are 25-35% smaller than JPEG with equivalent quality. Every image on your page should be WebP or AVIF.
3. Remove render-blocking CSS
Inline critical CSS, defer the rest. The biggest LCP killers are large CSS files that block rendering.
4. Use a CDN
A CDN moves your assets closer to your users. For a site hosted in the US serving Indian visitors, a CDN can cut LCP by 0.5-1.5 seconds.
INP: The New FID
INP replaced FID as a Core Web Vital in March 2024. It measures the time from user interaction to the next visual update. Poor INP is almost always caused by:
- Long JavaScript tasks on the main thread
- Expensive event handlers
- Layout recalculations triggered by scripts
CLS: Still Worth Fixing for UX
Even if CLS has weak ranking correlation, it destroys user experience. The most common sources:
- Images without dimensions set in HTML
- Fonts loading late (use font-display swap)
- Dynamic content insertion without reserved space
- Third-party widgets in unsized containers
Measuring Your Scores
- Chrome DevTools - Lighthouse - Performance tab
- PageSpeed Insights at pagespeed.web.dev — real user data + lab data
- Google Search Console — Core Web Vitals report shows real-world data at scale
Draftly Sites and Core Web Vitals
Sites generated by Draftly are optimised for Core Web Vitals by default:
- Hero videos use preload="none" to avoid blocking LCP
- Images are lazy-loaded below the fold
- Fonts are preloaded with font-display swap
- Critical CSS is inlined
Most Draftly sites score 85+ on PageSpeed Insights out of the box.
