How Image Size Affects Your Core Web Vitals
Images often account for 60% of a page's total weight. Optimize LCP, CLS, and FID to boost your Search Console performance and maximize AdSense revenue.
The Core Web Vitals Scoreboard
1. Largest Contentful Paint (LCP)
LCP measures the time it takes for the largest element on the screen to be fully rendered. For 85% of websites, this element is an image (hero banner, product image, or article feature).
Technical Insight
Unoptimized hero images can delay LCP by over 3 seconds on 4G connections.
The #1 cause of slow LCP is "Unsized Content" and "Legacy Formats". By switching from PNG to WebP and compressing the file, you can often cut LCP times by 50% or more.
2. Cumulative Layout Shift (CLS)
CLS measures visual stability. If your images don't have defined width and height attributes, the browser doesn't know how much space to reserve while the image loads.
Result: The text "jumps" down once the image appears, frustrating users and hurting your SEO.
The Fix: Define Dimensions
width="1200"
height="630"
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The Correlation: File Size vs. Mobile Speed
| Format | File Size (KB) | Load Time (Mobile) | LCP Score |
|---|---|---|---|
| Original PNG | 850 KB | 4.2s | POOR |
| Compressed JPG | 240 KB | 1.8s | NEEDS WORK |
| Optimized WebP | 45 KB | 0.6s | EXCELLENT |
Reduce File Size
Our AI-powered compressor reduces file sizes by up to 90% without visible quality loss.
Resize & Fix CLS
Automatically set correct width and height attributes to stop layout shifts and improve stability.
Search Console Pro-Tip
Google Search Console flags pages as "Poor" even if just 1 image is over the threshold. Use the PageSpeed Insights API to identify specific image URLs causing LCP failure before applying bulk fixes.