Core Web Vitals: what the three values mean and when they count as good
A page passes the Core Web Vitals when, at the 75th percentile of real Chrome visits, LCP is at most 2.5 seconds, INP at most 200 milliseconds and CLS at most 0.1. Google PageSpeed Insights shows these field data where enough visits exist, plus a lab test that points to the causes.
Thresholds at a glance
| Metric | Good | Needs improvement | Poor |
|---|---|---|---|
| LCP | ≤ 2.5 s | 2.5–4 s | > 4 s |
| INP | ≤ 200 ms | 200–500 ms | > 500 ms |
| CLS | ≤ 0.1 | 0.1–0.25 | > 0.25 |
Source: web.dev, judged at the 75th percentile of page views.
The usual causes and levers
LCP
Large image or slow server
Compress the main image, serve it as WebP or AVIF, do not lazy-load it, and make the server answer quickly (caching, hosting).
INP
Too much JavaScript
Remove scripts that are not needed, load third-party tools (chat, tracking) later, and split long tasks.
CLS
Content jumps
Give images, videos, ads and embeds a fixed width and height, and do not insert banners above content after loading.
Load time check: frequently asked questions
What are the Core Web Vitals?
Three metrics Google uses to describe the experience on a page: LCP (Largest Contentful Paint, loading), INP (Interaction to Next Paint, responsiveness) and CLS (Cumulative Layout Shift, visual stability). They are measured with real Chrome users and judged at the 75th percentile.
What are the thresholds?
According to web.dev: LCP is good up to 2.5 seconds and poor above 4 seconds; INP is good up to 200 milliseconds and poor above 500 milliseconds; CLS is good up to 0.1 and poor above 0.25. In between, a value needs improvement.
Why are field data and lab test different?
Field data come from the Chrome UX Report: real visits over the last 28 days, on real devices and networks. The lab test is a single Lighthouse run by Google with a simulated device and connection. Field data show what visitors experience; the lab test helps to find the causes.
Why does it say "no field data"?
Google only publishes real-user data for a page or domain once enough Chrome users with usage statistics enabled have visited it. Smaller websites often stay below that. The lab test still works.
Does the check load my website?
We do not. We pass the address to Google PageSpeed Insights; Google loads the page, measures it and returns the result. We store the checked address and the result in our tool log, never your IP address.