SEEN/.blackbox/skills/seo/references/cwv-thresholds.md

Core Web Vitals Thresholds (INP-era)

Use field data first (CrUX/RUM), then lab data for diagnosis.

Primary Metrics

Metric	Good	Needs Improvement	Poor
LCP	<= 2.5s	> 2.5s and <= 4.0s	> 4.0s
INP	<= 200ms	> 200ms and <= 500ms	> 500ms
CLS	<= 0.10	> 0.10 and <= 0.25	> 0.25

Supporting Diagnostics

Use these as diagnostic hints, not ranking stand-ins:

Metric	Suggested Target
TTFB	<= 0.8s
FCP	<= 1.8s
Total Blocking Time (lab)	<= 200ms
Main-thread long tasks	< 50ms each where possible

Measurement Hierarchy

1. Field data source priority:
   • CrUX (origin + URL level if available)
   • First-party RUM
2. Lab data source priority:
   • PageSpeed Insights lab profile
   • Lighthouse (mobile + throttled) for reproducible debugging

Audit Instructions

1. Compare mobile first, then desktop.
2. Classify each page template by CWV risk:
   • Critical: poor in any primary metric on key template
   • High: needs improvement on key conversion template
   • Medium: issue on secondary templates
3. Map root causes:
   • LCP: render-blocking CSS/JS, slow HTML, heavy hero image
   • INP: long JS tasks, expensive handlers, third-party script contention
   • CLS: unsized media, ad/embed shifts, late DOM injections
4. Propose one quick win and one structural fix per failing metric.

Rules

• Always use INP. Do not reference FID as a current optimization target.
• Avoid over-claiming from synthetic tests alone.
• If field data is unavailable, clearly label findings as provisional.