Image Compression

Image compression reduces file size without noticeably affecting visual quality. Because images often account for the largest portion of page weight, effective compression is one of the fastest ways to improve site speed.

Image Compression Matters

Large images slow down:

  • Page load time
  • Mobile performance
  • Largest Contentful Paint (LCP)

Industry Observation: On many content and e-commerce sites, images contribute 50–70% of total page size.

Example:

An online catalog compressed product images and switched to WebP. Average page size dropped by over 60%, and mobile load time improved from 4.1s to 2.3s.

Compression Best Practices

  • Use modern formats (WebP or AVIF)
  • Resize images to actual display dimensions
  • Apply lossless or controlled lossy compression
  • Avoid serving full-size images scaled down by CSS

Compression should happen before upload, not only at delivery.

Common Image Mistakes

  • Uploading raw camera images
  • Using PNG for photographic content
  • Relying solely on CMS auto-resizing