Core Web Vitals

What are Core Web Vitals?#

Core Web Vitals are Google's metrics for measuring real-world user experience on websites. They focus on three aspects:

• Loading: How quickly content appears
• Interactivity: How soon users can interact
• Visual Stability: How much the page shifts during load

Google uses Core Web Vitals as a ranking factor, making them important for SEO.

Largest Contentful Paint (LCP)#

LCP measures how long it takes for the largest visible content element to load. This is typically your hero image, headline, or main content block.

LCP Ratings

• Good: Under 2.5 seconds
• Needs Improvement: 2.5 - 4.0 seconds
• Poor: Over 4.0 seconds

How to Improve LCP

• Optimize and compress images
• Use a CDN for static assets
• Preload critical resources
• Reduce server response time

First Contentful Paint (FCP)#

FCP measures how long until the browser renders the first piece of content — any text, image, or SVG element. This is the user's first visual feedback that the page is loading.

FCP Ratings

• Good: Under 1.8 seconds
• Needs Improvement: 1.8 - 3.0 seconds
• Poor: Over 3.0 seconds

How to Improve FCP

• Reduce render-blocking resources (CSS, JS)
• Minimize critical CSS
• Remove unused CSS and JavaScript
• Enable text compression (gzip)

Cumulative Layout Shift (CLS)#

CLS measures visual stability — how much the page layout shifts while loading. High CLS is frustrating for users who may accidentally click the wrong element when content shifts.

CLS Ratings

• Good: Under 0.1
• Needs Improvement: 0.1 - 0.25
• Poor: Over 0.25

How to Improve CLS

• Always include width and height attributes on images
• Reserve space for ads, embeds, and iframes
• Avoid inserting content above existing content
• Use CSS transforms instead of layout properties for animations