Page Experience & Core Web Vitals

⚠️ INP replaced FID as a Core Web Vital on 2024-03-12. FID is retired.

Metrics are assessed at the 75th percentile of real-user field data (CrUX) over the trailing 28 days. A page passes when ≥75% of views hit "good".

Metric	Measures	Good	Needs Improvement	Poor
LCP (Largest Contentful Paint)	Loading	≤ 2.5 s	2.5–4.0 s	> 4.0 s
INP (Interaction to Next Paint)	Responsiveness	≤ 200 ms	200–500 ms	> 500 ms
CLS (Cumulative Layout Shift)	Visual stability	≤ 0.1	0.1–0.25	> 0.25

• Field data (CrUX) is what ranking uses. Lab data (Lighthouse/PSI) is for debugging and can differ — it can't measure INP or full-session CLS.
• Tools: Search Console CWV report (field), PageSpeed Insights (field+lab), CrUX API, Chrome DevTools, the web-vitals JS library.
• Passing CWV does not guarantee ranking — it's one input, a tiebreaker among comparably helpful results.

Framework tips: prevent CLS by reserving space (width/height or aspect-ratio); improve INP by breaking up long tasks and minimizing hydration/main-thread JS (Astro islands, Next.js RSC/streaming); improve LCP with priority/preload on the hero and SSR/SSG over client-only rendering.

Page experience (the broader picture)

There is no single "page experience" ranking signal. Contributing aspects: Core Web Vitals (the measured, ranking-relevant piece), HTTPS, mobile-friendly/responsive, no intrusive interstitials, reasonable ad density (main content distinguishable from ads). Among comparably helpful results, better page experience is a tiebreaker.

HTTPS is a lightweight ranking signal (historically <1% of queries). 301-redirect HTTP→HTTPS, add canonical HTTP→HTTPS, use HSTS, valid certs; never mix content or block HTTPS in robots.txt.

Mobile-first indexing: Google indexes/ranks using the mobile version. Only content present on mobile is used. Use responsive design (Google-recommended). Maintain content parity — same primary content, headings, structured data, image/video URLs + alt, titles/descriptions, and the same robots meta across versions. Accordions/tabs to save space are fine; deleting content is not. (Dynamic serving needs Vary: user-agent; m-dot needs extra canonical/alternate tags — most fragile.)

Related on Crawlinx

• Core Web Vitals: LCP, INP and CLS Explained (2026)
• Core Web Vitals in a Crawler: What Lab Data Shows
• Mobile-First Indexing: How to Pass Parity Checks
• HTTPS Migration SEO: A Before & After Checklist
• Security Headers and SEO: HTTPS, HSTS, CSP
• content.thin

Sources

1. web.dev — Web Vitals
2. Google Search Central — Understanding page experience in Google Search results
3. web.dev — Interaction to Next Paint (INP)
4. Google Search Central — Mobile-first indexing best practices