Google Lighthouse and Core Web Vitals describe different parts of performance assessment. Understanding the data behind each helps you interpret the results.
On Google Lighthouse
Google Lighthouse is an open-source tool that runs simulated lab tests. It reports metrics such as FCP and LCP alongside checks for PWA, best practices, SEO, and accessibility.
Lighthouse reports a performance score from 0 to 100.
Metrics discussed in Lighthouse reports include First CPU Idle, Speed Index, and Time to Interactive.
The other audits identify accessibility, SEO, and best-practice issues to investigate.
Core Web Vitals
Core Web Vitals describe loading performance, responsiveness, and visual stability. Real user data shows how visitors experience those aspects of a page.
The metrics discussed here are Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift.
Largest Contentful Paint (LCP) measures when the main content appears. The target is 2.5 seconds or less.
First Input Delay (FID) measures the delay between the first interaction and the browser beginning to respond. The target is less than 100ms.
Cumulative Layout Shift (CLS) measures visual stability. Keep the score at or below 0.1.
Lighthouse Vs. Core Web Vitals
Google Lighthouse covers performance alongside SEO, accessibility, and best practices.
Core Web Vitals focus on specific aspects of the page experience. Use them alongside the broader Lighthouse audit.
Interpret the Data Behind the Score
Check whether a result comes from a controlled test or real visitors before comparing it with another report.
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