Understanding Google Core Web Vitals
Core Web Vitals are a set of real-world, user-centered metrics that quantify key aspects of user experience. They measure loading performance, interactivity, and visual stability of your web pages.
The Three Core Web Vitals
Largest Contentful Paint (LCP) LCP measures loading performance. It marks the point when the largest content element in the viewport becomes visible. For good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.
First Input Delay (FID) FID measures interactivity. It quantifies the time from when a user first interacts with a page (clicks a link, taps a button) to the time the browser is able to respond to that interaction. FID should be less than 100 milliseconds.
Cumulative Layout Shift (CLS) CLS measures visual stability. It quantifies how much visible content shifts around on the page during loading. A good CLS score is less than 0.1.
How to Improve Core Web Vitals
Improve LCP:
- Optimize and compress images
- Eliminate render-blocking resources
- Improve server response time
- Use a CDN
Improve FID:
- Break up long tasks
- Optimize JavaScript execution
- Use web workers
- Defer non-critical JavaScript
Improve CLS:
- Set explicit dimensions for images and embeds
- Reserve space for dynamic content
- Avoid inserting content above existing content
Monitoring Your Scores
Use tools like Google Search Console, PageSpeed Insights, and Lighthouse to monitor your Core Web Vitals regularly.