Free Core Web Vitals Measurement Tool
Measure LCP, CLS, INP and performance scores.
Diagnose page speed for both mobile and desktop.
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What are Core Web Vitals?
Google's official page-experience metrics that score a page's load time, visual stability and responsiveness using three signals: LCP, CLS and INP.
- Three metrics
- LCP (loading), CLS (stability), INP (responsiveness)
- Good thresholds
- LCP ≤ 2.5s, CLS ≤ 0.1, INP ≤ 200ms
- Source
- Google PageSpeed Insights API
- Ranking impact
- Official ranking factor since June 2021
Best for: Developers and site owners who suspect their pages load or respond too slowly
What Are Core Web Vitals?
Three user experience metrics defined by Google. Included as a search ranking factor since 2021.
LCP (Largest Contentful Paint)
Time until the main content is visible. Under 2.5 seconds is "good". Image optimization and server response time are key.
CLS (Cumulative Layout Shift)
How much the layout shifts during loading. Under 0.1 is "good". Set image dimensions and reserve ad space.
INP (Interaction to Next Paint)
Response time to user interactions. Under 200ms is "good". Optimize heavy JavaScript and reduce main thread load.
Performance Score
Google Lighthouse-based 0-100 score. 90+ is "good". Evaluated separately for mobile and desktop.
Why Core Web Vitals Matter
Core Web Vitals are a Google search ranking factor. With equal content quality, sites with better Core Web Vitals scores rank higher, especially in mobile search.
Speed improvements directly impact conversions. Google's research shows that when page load increases from 1 to 3 seconds, bounce rate increases by 32%.
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Measure your site's Core Web Vitals
Accurately measure LCP, CLS, and INP using Google PageSpeed Insights API. Get actionable improvement points.