30-Second Summary
What you'll learn from this article
- Core Web Vitals directly impact Google rankings
- LCP should be under 2.5 seconds - image optimization is critical
- FID should be under 100ms - requires JavaScript optimization
- CLS should be under 0.1 - define image dimensions upfront
- Measure regularly with PageSpeed Insights and Lighthouse
Core Web Vitals are three critical metrics that Google incorporated into its ranking algorithm in 2021 to measure user experience on web pages. In this guide, we'll examine each metric in depth and provide practical optimization strategies.
What is LCP (Largest Contentful Paint)?
LCP measures how long it takes for the largest content element on your page (usually hero image or heading) to load and become visible. Google's recommended ideal value is 2.5 seconds or less.
FID (First Input Delay) Optimization
FID measures the time between user's first interaction with the page (button click, focus on form field) and when the browser can respond to that interaction. The ideal value is under 100ms.
CLS (Cumulative Layout Shift) Issues and Solutions
CLS measures how much content elements shift during page load. Ads, fonts, and images are the most common causes of CLS. The ideal value is 0.1 or less.
Measurement Tools and Monitoring
You can use Google PageSpeed Insights, Lighthouse, and Chrome DevTools to measure Core Web Vitals. For real user data, the Core Web Vitals report in Google Search Console is the most reliable source.
Core Web Vitals optimization is not a one-time task but a continuous process. Check metrics whenever you add new features or content and make necessary improvements.