How to Compress Image for WordPress Upload

Images are the single largest contributor to slow WordPress sites. According to HTTP Archive data, images account for over 60% of the average web page's total file size. Compressing images before uploading them to WordPress is one of the highest-impact optimisations you can make to your site's loading speed — and it takes just seconds per image.

WordPress Image Size Guidelines

For most WordPress blogs and business websites, images should be no larger than 1200px wide and under 200KB in file size. Featured images (often displayed at 1200×628px) should compress to under 150KB. Product images for WooCommerce stores should stay under 300KB per image.

How to Compress Images for WordPress

1. Resize your image to the appropriate width first using the Image Resizer.
2. Open the Image Compressor at imgresizr.com.
3. Upload your resized image and set quality to 75–80%.
4. Download the compressed image — it should now be well under 200KB.
5. Upload to WordPress via the Media Library. WordPress generates additional sizes automatically.

Beyond Manual Compression

Convert to WebP for WordPress

All modern browsers and WordPress (since version 5.8) support WebP natively. Converting JPG images to WebP before uploading results in files that are 25–35% smaller at the same visual quality. This is one of the easiest wins for your WordPress PageSpeed score.

Install an Image Optimisation Plugin

For images already in your WordPress media library, a plugin like Smush, ShortPixel, or Imagify can batch-compress existing images server-side. These complement your pre-upload compression workflow rather than replacing it — double compression gives you the best possible results.