Web performance depends heavily on properly optimised images — the right dimensions and file size directly impact page speed and user experience. This guide covers the exact specifications for CDN Delivery and shows you how to compress your images to the correct dimensions using the free tools at imgresizr.com.
Image Specifications for CDN Delivery
| Parameter | Recommended Value |
|---|---|
| Hero / banner image | 1920 × 1080 px |
| Blog post image | 1200 × 628 px |
| Thumbnail | 400 × 300 px |
| Max file size (fast load) | 200 KB |
| Format (photos) | WebP or JPG |
| Format (graphics) | PNG or SVG |
How to Compress Images for CDN Delivery at imgresizr.com
Upload your image to imgresizr.com. Select the Compress tab. Enter the correct dimensions for CDN Delivery as shown in the table above. Use the lock icon to maintain the aspect ratio if you only know one dimension. Click Compress to process your image. Download the result — your image is now correctly sized for CDN Delivery. All processing happens in your browser; your image is never uploaded to any server.
Tips for CDN Delivery
- Use WebP format instead of JPG for better quality-to-file-size ratio on modern browsers
- Always specify width and height attributes on img tags to prevent layout shift (CLS)
- Serve different image sizes for mobile and desktop using srcset for best performance
- Lazy-load images below the fold — they should not delay the initial page load
- Run Lighthouse audits after optimising images to verify Core Web Vitals improvement
Compress images for CDN Delivery instantly, free at imgresizr.com.