Compressing files one at a time is tedious. When you have dozens of photos to upload to a website, multiple PDFs to email to a client, or a folder of documents that is eating up your storage, batch compression saves hours of manual work.
This guide covers how to batch compress both images and PDFs — for free, online, without installing anything.
Why Batch Compress?
Time savings: Compressing 50 files individually might take an hour of clicking, waiting, and downloading. Batch compression processes them all in one operation — typically in minutes. Consistent quality: When you compress files one at a time, it is easy to accidentally use different quality settings. Batch compression applies the same settings to every file for consistent results.
Storage optimization: A folder of 100 product photos at 5MB each is 500MB. Compressing them to 1.5MB each saves 350MB — significant for cloud storage costs and local disk space. Faster uploads and transfers: Compressed files upload faster to websites, send faster via email, and transfer faster between devices.
How to Batch Compress Images
Step 1: Select your images. Go to the Image Compress tool (https://www.iamuu.com/image/compress/) at U-Ultra/Unity. Upload all the images you want to compress — JPG, PNG, and WebP are supported.
Step 2: Choose compression settings. Set the quality level: 80-85 for web images (good balance of size and quality), 60-75 for maximum compression (visible but acceptable quality loss), and 90-95 for minimal compression (near-original quality for print). For PNG images, you can also adjust the compression level separately.
Step 3: Compress and download. Click Submit. All images are compressed in parallel. Download them as a ZIP file or individually.
How to Batch Compress PDFs
Step 1: Upload your PDFs. Go to the PDF Batch Compress tool (https://www.iamuu.com/pdf/batch-compress/) at U-Ultra/Unity. Upload multiple PDF files at once.
Step 2: Choose compression mode. Low Compression: Best quality, smallest size reduction — ideal for print-ready documents. Medium Compression: Balanced — good for business documents and reports. High Compression: Smallest file size — great for email attachments and web upload.
Step 3: Process and download. Click Submit. Each PDF is compressed independently with the same settings. Download all compressed files as a ZIP.
Batch Compression Tips
Test with one file first. Run a single file through batch compression to verify the quality settings are right. Once confirmed, process the whole batch. Organize before compressing. Group files by type and desired quality. Photos for web might need different settings than archival documents.
Check compressed files before deleting originals. Always spot-check a few compressed files at 100% zoom before deleting the original uncompressed versions. Use for specific purposes: batch compress for email (aggressive compression, small files), web upload (medium compression, balance), and archiving (light compression, high quality).
For single-file compression with more granular control, use the individual compress tools: Image Compress (https://www.iamuu.com/image/compress/) for individual images with per-file settings, and PDF Compress (https://www.iamuu.com/pdf/compress/) for single PDFs with three compression levels.
Ready to batch compress? Try the free batch tools at U-Ultra/Unity — compress multiple files at once, no registration required.