Core Web Vitals Checker
Test any public page with Google’s own PageSpeed Insights engine and see its performance score, LCP, CLS and TBT. No API key needed on your side.
What "good" looks like
| Metric | Good | Needs improvement | Poor |
|---|---|---|---|
| LCP | ≤ 2.5s | 2.5s–4s | > 4s |
| CLS | ≤ 0.1 | 0.1–0.25 | > 0.25 |
| TBT | ≤ 200ms | 200ms–600ms | > 600ms |
These are lab-based numbers from a single simulated run, not the real-user field data Google actually uses for ranking (that comes from the Chrome User Experience Report). Treat this as a diagnostic snapshot, and check Google Search Console's Core Web Vitals report for your real, aggregated visitor data.
How to use the Core Web Vitals Checker
- Enter the full URL of the page to test.
- Choose mobile or desktop and run the check (15–30 seconds).
- Fix the metric in the “poor” range first, usually the largest image or blocking scripts.
Frequently asked questions
Is this the same data Google uses for ranking?
This is lab data from one simulated visit. Google’s ranking signal uses real-visitor data from the Chrome UX Report, which you can see in Search Console.
Why do scores change between runs?
Network and server timing vary a little on every test. Run it two or three times and look at the typical result.
Which metric matters most?
Largest Contentful Paint (loading speed) is usually the one to fix first on content sites. It is most often caused by a large hero image.