Choosing the Right Image Format for Websites

Why Image Format Matters

Images typically account for 50-90% of a webpage's total size. Choosing the wrong format can:

• Slow down page load times
• Hurt SEO rankings (Core Web Vitals)
• Increase hosting bandwidth costs
• Frustrate users on slow connections

Format Quick Reference

When to Use Each Format

JPG (JPEG)

Best for: Photographs and complex images

• Excellent compression for photos
• Millions of colors
• No transparency support
• Lossy compression (quality degrades with each save)

Use when: The image is a photo or has lots of gradients/colors

PNG

Best for: Graphics, logos, screenshots

• Lossless compression (no quality loss)
• Full transparency support
• Larger file sizes for photos
• Great for text and sharp edges

Use when: You need transparency, or the image has text/sharp edges

WebP

Best for: Almost everything (if browser support is OK)

• 25-35% smaller than JPG at same quality
• Supports both lossy and lossless compression
• Full transparency support
• Supported by all modern browsers (95%+ coverage)

Use when: You want the best balance of quality and file size

SVG

Best for: Icons, logos, simple illustrations

• Vector format (scales infinitely)
• Tiny file sizes for simple graphics
• Can be styled with CSS
• Not suitable for photographs

Use when: The image can be represented as vectors (logos, icons)

Conversion Guide

Need to convert between formats? Here's what to know:

Photo (JPG) → WebP

• Reduces file size 25-35%
• Maintains quality
• Use ImgConvert for easy conversion

PNG → WebP

• Significant size reduction
• Maintains transparency
• Great for web graphics

PNG → JPG

• Removes transparency (adds white/chosen background)
• Reduces file size significantly
• Some quality loss

Any → SVG

• Only works for vector graphics
• Can't convert photos to SVG meaningfully
• Must be created in vector software (Illustrator, Figma)

Responsive Images Strategy

Modern websites should serve different formats/sizes:

<picture>
  <source srcset="image.webp" type="image/webp">
  <source srcset="image.jpg" type="image/jpeg">
  <img src="image.jpg" alt="Description">
</picture>

This serves WebP to browsers that support it, JPG to others.

File Size Guidelines

Common Mistakes

• Using PNG for photos - Wastes bandwidth, use JPG or WebP
• Using JPG for screenshots - Text gets artifacts, use PNG
• Not compressing images - Always optimize before uploading
• Using GIF for photos - Limited to 256 colors, looks terrible
• Ignoring WebP - Missing out on 30% size savings

Conclusion

The "best" format depends on your specific image:

• Photos: WebP > JPG
• Graphics/Screenshots: WebP > PNG
• Icons/Logos: SVG > PNG
• Simple animations: WebP > GIF

When in doubt, WebP is usually the right choice for web. It combines the best of JPG and PNG with smaller file sizes.