Core Web Vitals Checker — Test Your Site for Free
Google uses Core Web Vitals as a ranking signal. If your site fails, you're losing search visibility. Check your scores instantly.
What are Core Web Vitals?
Three metrics Google uses to measure real-user experience:
- LCP (Largest Contentful Paint) — How fast the main content loads. Target: under 2.5 seconds.
- CLS (Cumulative Layout Shift) — How much the page jumps around while loading. Target: under 0.1.
- INP (Interaction to Next Paint) — How fast the page responds to clicks and taps. Target: under 200ms. Replaced FID in March 2024.
What SiteAudit AI tells you that PageSpeed doesn't
PageSpeed Insights
"LCP: 4.2s — Needs improvement"
SiteAudit AI
"Your hero image is 3.1MB in JPEG format. Converting to WebP and adding lazy loading to below-fold images would reduce LCP to approximately 2.0s. Here's how to do it in Next.js / WordPress / plain HTML."
The difference is actionable recommendations in plain English vs raw numbers.
Common CWV fixes
Slow LCP
- Compress and convert hero images to WebP
- Preload the LCP element
- Reduce server response time (TTFB)
High CLS
- Add width and height to all images and videos
- Avoid injecting content above existing content
- Use font-display: swap for web fonts
Slow INP
- Reduce JavaScript execution time on interaction
- Break up long tasks into smaller chunks
- Defer non-critical third-party scripts
Frequently asked questions
Do Core Web Vitals affect SEO rankings?
Yes. Google confirmed CWV is a ranking signal. Sites that fail CWV consistently saw 20-30% more traffic loss during the December 2025 core update.
How often should I check Core Web Vitals?
After every deployment, and monthly as a baseline. Third-party scripts and CMS updates can regress your scores without you noticing.
Want a broader audit beyond just CWV? Try the free website audit or review the complete website audit checklist.