Core Web Vitals Test
Whether a page passes the Core Web Vitals is decided by real visitors, not by a single lab test. This Core Web Vitals test checks the LCP, INP and CLS of your website with field data from the Chrome UX Report and also tests the same pages in the lab, so you see whether your site passes and, if it does not, why.
Core Web Vitals test: LCP, INP and CLS at the 75th percentile
Google rates page experience with three metrics. Largest Contentful Paint (LCP) measures when the largest visible element has loaded, Interaction to Next Paint (INP) how quickly the page responds to clicks and input, and Cumulative Layout Shift (CLS) how much the layout moves while loading. A page passes when, at the 75th percentile of real page loads, LCP is at most 2.5 seconds, INP at most 200 milliseconds and CLS at most 0.1.
Field data first, lab data for the diagnosis
Rankings use the field data of real Chrome users over the last 28 days. The checker shows it per page and, where a single URL has too few visitors, falls back to the whole origin. The lab test next to it explains the cause: which image sets the LCP, which script blocks the main thread, which element shifts.
Core Web Vitals of other websites for comparison
In PerfDelta's measurements, 49% of 4,277 websites pass all three Core Web Vitals. 74% have a good INP and 71% a good LCP. All figures are in the website speed statistics.
FAQ
How do I check the Core Web Vitals of my website?
Enter the address above. PerfDelta finds further pages through your sitemap, reads the field data from the Chrome UX Report and also tests the pages with Lighthouse, on mobile and desktop.
Why does the test show no field data for my page?
The Chrome UX Report only covers pages and origins with enough Chrome visitors. If a URL has no data, the test shows the values of the whole origin. If that is missing too, the lab data remains as a guide.
How long until improvements show up?
Field data covers 28 days, so an improvement appears gradually over about four weeks. With an account on the Solo plan or higher, PerfDelta tracks the values every day.
How do your competitors compare? The Core Web Vitals Benchmark puts up to five websites side by side using real-user data.
Guides for every metric and finding are in the Website Speed Optimization.
PerfDelta is built by Christian Schreiber, who has been working on SEO and web performance for more than 15 years.
A free account saves your tests and shows how your values change from one test to the next. Daily monitoring with field data and alerts starts with the Solo plan.