Core Web Vitals Checker
One of the free tools from KinetixSEO, an SEO and AI-citation (GEO) checker. Loads any page in a real headless browser and measures LCP, CLS, INP, FCP and TTFB — the loading-speed and visual-stability metrics Google uses as a direct ranking signal.
Frequently asked questions
What are Core Web Vitals?
Google's standardized metrics for real-world page experience: Largest Contentful Paint (LCP, loading speed), Cumulative Layout Shift (CLS, visual stability), and Interaction to Next Paint (INP, responsiveness) — plus First Contentful Paint and Time to First Byte as supporting signals.
How does this tool measure them?
It loads your page in a real headless Chrome browser and reads the same Performance API entries Chrome itself exposes, then rates each metric against Google's published good/needs-improvement/poor thresholds — a single lab measurement, not real-user field data.
Why is INP sometimes "unknown"?
INP measures responsiveness to real user interaction (clicks, taps, key presses). A synthetic lab run with no interaction has nothing to measure, so INP only populates here when the page itself fires interaction-like events during load — for real INP data at the 75th percentile, use Google's CrUX API.
Why do Core Web Vitals matter for SEO?
They're a confirmed Google ranking signal (the Page Experience update), and poor LCP/CLS/INP directly hurts conversion and bounce rate regardless of ranking — slow, jumpy pages lose visitors before they read anything.
How is this different from PageSpeed Insights?
Conceptually similar — both run a real browser and report lab Core Web Vitals. This tool is scoped to the core metrics with instant, no-signup results; PageSpeed Insights additionally blends in real-user CrUX field data and a broader Lighthouse audit.
This is one check from KinetixSEO's full SEO/GEO audit. Want the complete picture — AI-citation readiness, technical SEO health, and tailored fixes? Run the free full checker.