Batch PDF Compression: How to Compress Multiple Files at Once

Compressing one PDF is easy. But what about 50? Or 500? Batch compression saves hours when you’re dealing with large document sets.

This guide covers efficient techniques for compressing multiple PDFs at once.

When You Need Batch Compression

• Digitization projects: Scanning years of paper records
• Legal discovery: Processing document collections
• Academic research: Managing source materials
• Business archives: Reducing storage costs
• Migration projects: Moving to new systems with size limits

Batch Compression Methods

Method 1: SecureCompress Pro

SecureCompress Pro includes batch processing for multiple PDFs.

How it works:

1. Select multiple files or a folder
2. Set target size (applies to all)
3. Choose output location
4. Start batch processing
5. Review results

Pros:

• Consistent settings across all files
• Progress tracking
• Local processing (privacy)
• Target-size precision

Best for: Users who need exact size control across many files.

Get SecureCompress Pro →

Method 2: Automator (Mac, Free)

macOS Automator can batch-compress using Preview’s engine.

Setup:

1. Open Automator
2. Create new “Folder Action”
3. Add “Apply Quartz Filter to PDF Documents”
4. Select “Reduce File Size”
5. Save the workflow

Pros:

• Free
• Automatic (processes new files)
• Built into macOS

Cons:

• No size control
• Often over-compresses
• Inconsistent results

Best for: Quick, non-critical batch jobs.

Method 3: Command Line (Ghostscript)

For technical users, Ghostscript offers powerful batch capabilities.

Basic command:

for f in *.pdf; do
  gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 \
     -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH \
     -sOutputFile="compressed_$f" "$f"
done

Quality presets:

• /screen: Lowest quality, smallest size
• /ebook: Medium quality (recommended)
• /printer: High quality
• /prepress: Highest quality

Pros:

• Free and open-source
• Highly customizable
• Scriptable

Cons:

• Technical setup required
• No GUI
• No target-size option

Best for: Technical users with scripting needs.

Method 4: Adobe Acrobat Pro

Acrobat’s Action Wizard can process multiple files.

Setup:

1. Tools → Action Wizard
2. Create New Action
3. Add “Optimize PDF” step
4. Configure settings
5. Run on folder

Pros:

• Professional tool
• Many options
• Reliable results

Cons:

• Expensive subscription
• No target-size option
• Can be slow

Best for: Enterprise users with Acrobat licenses.

Batch Processing Best Practices

1. Test First

Before processing hundreds of files:

1. Select 5-10 representative samples
2. Run batch compression
3. Verify quality and size
4. Adjust settings if needed
5. Then process the full set

2. Organize Input Files

Create a clear folder structure:

/Documents_to_Compress/
  /Batch_001/
  /Batch_002/
  /Batch_003/

This helps track progress and troubleshoot issues.

3. Plan Output Location

Don’t overwrite originals:

/Original_Documents/
/Compressed_Documents/

Keep originals until you’ve verified all compressed files.

4. Use Consistent Settings

For uniform results:

• Same target size (or percentage)
• Same DPI setting
• Same color mode
• Same quality level

5. Monitor Progress

For large batches:

• Check periodically for errors
• Verify sample files during processing
• Note any files that fail

Handling Different Document Types

Mixed Document Sets

If your batch contains different document types:

Option A: Sort first, then batch

1. Separate scanned vs. text-based
2. Separate color vs. grayscale
3. Process each group with appropriate settings

Option B: Use conservative settings

1. Apply settings that work for all types
2. Accept that some files won’t compress optimally
3. Faster but less efficient

Recommended Settings by Type

Document Type	Mode	DPI	Target
Scanned text	Grayscale	200	70% reduction
Scanned color	Color	200	60% reduction
Text-based	N/A	N/A	20% reduction
Mixed	Color	200	50% reduction

Estimating Time and Results

Processing Time

Rough estimates (varies by hardware):

Files	Pages Total	Estimated Time
10	100	1-2 minutes
50	500	5-10 minutes
100	1,000	10-20 minutes
500	5,000	1-2 hours

Size Reduction

Typical results for scanned documents:

Original Total	After Compression	Reduction
1 GB	100-200 MB	80-90%
10 GB	1-2 GB	80-90%
100 GB	10-20 GB	80-90%

Text-based PDFs compress less (20-40% reduction).

Troubleshooting Batch Jobs

Some Files Failed

Common causes:

• Corrupted source files
• Password-protected PDFs
• Unusual PDF formats
• Disk space issues

Solution: Process failed files individually to identify issues.

Inconsistent Results

Some files much larger/smaller than expected:

Cause: Different source characteristics Solution: Sort by type and process separately

Quality Issues

Some files are blurry:

Cause: Settings too aggressive for some documents Solution: Increase target size or DPI, reprocess affected files

Process Crashed

Causes:

• Memory exhaustion
• Disk full
• Corrupted file in batch

Solutions:

• Process in smaller batches
• Free up disk space
• Identify and remove problematic files

Automation Tips

Scheduled Processing

Set up automatic compression for new files:

On Mac (Folder Actions):

1. Create Automator folder action
2. Point to incoming documents folder
3. New files auto-compress

On Windows (Task Scheduler):

1. Create batch script
2. Schedule to run nightly
3. Process files in designated folder

Integration with Scanning

If you’re scanning documents:

1. Scan to a “raw” folder
2. Batch compress to “processed” folder
3. Archive or delete raw files

Cloud Integration

For cloud-synced folders:

1. Compress before uploading
2. Reduces sync time
3. Saves cloud storage space

Cost-Benefit Analysis

Time Savings

Method	Setup Time	Per-File Time	100 Files
Manual	0	30 sec	50 min
Batch tool	5 min	3 sec	10 min
Automated	30 min	0	0 (ongoing)

Storage Savings

Compressing 100GB of scanned documents:

• Before: 100GB storage cost
• After: 15GB storage cost
• Savings: 85% of storage costs

Summary

For efficient batch PDF compression:

1. Choose the right tool for your volume and needs
2. Test on samples before full batch
3. Organize files clearly
4. Use consistent settings for uniform results
5. Keep originals until verified
6. Automate for ongoing needs

Batch compression turns hours of manual work into minutes of automated processing.

Get SecureCompress Pro — batch compression with target-size precision.