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Core Web Vitals

Core Web Vitals is a set of metrics introduced by Google that aim at helping you measure the quality of user experience on a website. The metrics themselves are a part of a larger set of metrics, Web Vitals, and are defined as the three most important metrics to measure the quality of user experience.

The Core Web Vitals Metrics

The three core web vitals metrics are the largest contentful paint, first input delay, and cumulative layout shift, and they measure loading, interactivity, and visual stability of the webpage.

  • Largest Contentful Paint, LCP: measures loading performance with the perceived time the page’s main content is likely loaded. It should be less than 2.5s.
  • First Input Delay, FID: measures interactivity. The time it takes before the user can provide input and should be under 100ms.
  • Cumulative Layout Shift, CLS: measures visual stability. The layout should be visually stable and keep a CLS of less than 0.1.

Measuring Core Web Vitals

You can measure the core web vitals using the web vitals open-source library, or you can use the Chrome web vitals browser extension, which requires no coding from your side.

PageSpeed Insights now also measures the core web vitals metrics directly. Or use GTmerix.

PageSpeed Insights measuring core web vitals

Measuring Global Site Performance

When optimizing for site speed, it is vital to measure the performance from different locations globally. Lighthouse metrics is an excellent tool for doing so, and it measures the site speed from six other locations giving you a good overview of the site performance from around the globe.

Global site speed measured with Lighthouse metrics

Importance of Core Web Vitals

Improving Core Web Vitals has a positive impact on your user experience, and it may have an impact on your search engine ranking. Google already started a couple of times that Page Experience signals (and Core Web Vitals as a part of them) will not be stronger ranking signals than content-related ones.

While we don’t know the actual weight, they are bringing with them in the ranking algorithm, but we know they matter. Have a look at our research on how site speed affects SEO and Google rankings.

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