Compressing images one at a time is tedious. Whether you're optimizing a website, preparing a photo gallery, or reducing storage usage, batch compression saves hours of work.

Why Batch Compress?

Save time - Process hundreds of images in minutes
Consistent results - Same settings applied to all images
Efficient workflow - Set it and forget it
Bulk optimization - Perfect for website migrations

Online Batch Compression with fatpng

fatpng lets you compress up to 10 images at once, directly in your browser:

Select multiple files - Drag and drop up to 10 images
Choose your settings - Set quality level and output format
Compress all - Click one button to process everything
Download - Get individual files or a ZIP archive

Benefits of Browser-Based Compression

Privacy - Images never leave your computer
No installation - Works on any device
Free - No limits on usage
Fast - WebAssembly-powered processing

Desktop Tools for Large Batches

For hundreds or thousands of images, desktop tools are more practical:

ImageOptim (Mac)

Free and open source
Drag and drop interface
Combines multiple optimization tools
Lossless by default

FileOptimizer (Windows)

Free and comprehensive
Supports many file types
Right-click integration

Squoosh CLI

Google's command-line tool for automation. Install via npm and run on your image folders.

Command Line Batch Processing

Using ImageMagick

Loop through all JPEGs in a folder and compress them with a quality setting of 80:

Use the convert command with -quality flag
Process files in a for loop
Output to a new filename to preserve originals

Using cwebp (Convert to WebP)

Google's cwebp tool converts images to WebP format:

Set quality with -q flag (0-100)
Batch process using shell loops
Achieves 25-35% better compression than JPEG

Using pngquant (PNG)

Pngquant uses lossy compression to dramatically reduce PNG sizes while maintaining quality.

Build Tool Integration

Webpack

Use the image-minimizer-webpack-plugin to automatically compress images during your build process. Configure it with your preferred encoders like MozJPEG and WebP.

Gulp

The gulp-imagemin plugin processes images as part of your Gulp workflow. Set optimization levels for PNG and quality for JPEG.

Batch Compression Best Practices

1. Organize First

Before compressing, organize your images:

Separate by type (photos, graphics, screenshots)
Remove duplicates
Delete unnecessary images

2. Keep Originals

Always keep a backup of your original files before batch processing. Compression is typically irreversible.

3. Test Settings First

Before processing hundreds of images:

Compress a small sample (5-10 images)
Check quality at actual display size
Adjust settings if needed
Then process the full batch

4. Use Appropriate Settings

Image Type	Recommended Quality
Hero images	80-85%
Product photos	75-80%
Blog images	70-80%
Thumbnails	60-70%
Background images	60-75%

5. Consider Output Format

Batch converting to WebP can provide additional savings:

Convert JPEG to WebP for 25-35% more savings
Keep originals as fallbacks

Handling Mixed File Types

When batch processing folders with mixed formats:

JPEG files: Apply lossy compression (70-80%)
PNG files: Apply lossless optimization first
Already-WebP: Usually skip (already optimized)
GIF animations: Consider converting to WebP

Automation for Ongoing Optimization

Set up automatic compression for new images:

CI/CD pipeline: Compress on every build
Git hooks: Compress before committing
Watch folders: Auto-compress new uploads
CDN processing: Cloudflare, imgix, Cloudinary

Conclusion

Batch compression is essential for any project with more than a handful of images. Start with fatpng for quick online processing, and set up automated tools for ongoing optimization. Your users (and bandwidth bills) will thank you.

How to Batch Compress Multiple Images at Once