Web Vitals

Core Web Vitals are a set of key website performance metrics from Google that assess page load speed, interactivity, and visual stability.

Core Web Vitals include LCP, INP, and CLS. A Lighthouse lab run also provides FCP, TBT, Speed Index, and server response time. We show INP separately if the API returns user data.

Google benchmarks: LCP no more than 2,5 seconds, INP no more than 200 ms, and CLS no more than 0,1. User data is assessed at the 75th percentile separately for each device type. A single good Lighthouse run doesn’t confirm that Core Web Vitals are passing.

Optimize images, reduce render-blocking CSS and JavaScript, use caching and lazy loading, and improve server response time.

Check the metrics after major interface changes, adding new scripts, and before important releases.

INP is shown only when user data is available in the source response. There may not be enough measurements for a new or rarely visited URL. This does not mean INP is zero or that the page has an error; lab TBT is not substituted for it.

Lab results are affected by the selected device, network, server response, and third-party scripts. Run the test again in the same mode and compare the findings. User data is collected over a period of time and may differ from a single lab run.