Core Web Vitals
Short definition
Core Web Vitals are Google's three metrics for measuring a page's loading speed, interaction response and visual stability.
It consists of three metrics: LCP measures how long the main content takes to appear, INP measures how fast the page responds to clicks and taps, and CLS measures how much elements shift while the page loads. Google tracks all three in Search Console's Core Web Vitals report and from real user data.
You meet these metrics in PageSpeed Insights and Search Console. The official thresholds are 2.5 seconds for LCP, 200 milliseconds for INP and 0.1 for CLS; pages under these limits are marked good.
It is often confused with page speed, but it is not a single number: it is three separate dimensions of experience assessed together, one can pass while another fails.
The most common mistake is trusting a single lab test, run once on one device under ideal conditions, and assuming the score reflects reality; Google's ranking assessment instead relies on field data gathered from real visitors. The right approach is to monitor the field report in Search Console regularly and use lab testing only to diagnose specific problems.
Why it matters
A site that loads slowly or responds late to a tap loses visitors, and Google ranks such sites lower in search. Tracking Core Web Vitals affects both conversions and rankings directly.
Illustrative example
A spa chain's booking page saw completions drop once LCP passed four seconds; compressing the hero image brought it back under two seconds and bookings recovered.
