Free Core Web Vitals Checker
One of the free tools from KinetixSEO, an SEO and AI-citation (GEO) checker. This Core Web Vitals test / LCP CLS INP 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.
What you'll get
Core Web Vitals
- LCP
- 3120ms
- CLS
- 0.04
- INP
- 180ms
- FCP
- 1240ms
- TTFB
- 620ms
Needs improvement
Good
Good
Good
Needs improvement
What the Free Core Web Vitals Checker checks
- Largest Contentful Paint (LCP) measured against Google's 2.5s "good" threshold
- Cumulative Layout Shift (CLS) measured against the 0.1 "good" threshold
- Interaction to Next Paint (INP) measured against the 200ms "good" threshold
- First Contentful Paint (FCP) and Time to First Byte (TTFB) as supporting diagnostics
- All metrics measured with a real headless-Chrome run against the live page, not a lab estimate
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.
Related reading
Go deeper
This free check looks at one signal in isolation. KinetixSEO's paid report combines every signal below into one prioritised fix list and tracks it over time.
See the full paid report for this →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.