Will compression make my scanned text unreadable?

Not if done correctly. Our compression algorithms are optimized for document images. Text remains sharp and readable. Always verify the output, especially for important documents.

Can I compress already compressed scans?

Yes, but with diminishing returns. If a scan was already heavily compressed, you may not see significant size reduction. Our tool will still optimize what it can.

What about scans with handwriting?

Handwritten text compresses well with Low to Medium settings. The key is ensuring sufficient contrast in the original scan. Grayscale mode often works best for handwriting.

Should I compress before or after OCR?

Apply OCR first, then compress. OCR needs the original image quality for accurate text recognition. Once text is extracted, you can compress more aggressively.

Compress Scanned Documents - Reduce PDF Size from Scanner

Scanned documents are notorious for their large file sizes. A simple one-page scan can easily exceed 5MB, and multi-page documents can balloon to hundreds of megabytes. This happens because scanners capture documents as images, storing every pixel of detail.<br><br>This guide covers everything you need to know about compressing scanned PDFs effectively while preserving legibility.

Why Are Scanned PDFs So Large?

Image-based content: Unlike native PDFs with vector text, scans store everything as raster images
High DPI settings: Scanners often default to 300-600 DPI, creating massive files
Color depth: Full-color scans use 24 bits per pixel vs. 1 bit for black and white
No compression: Many scanners save in uncompressed or lightly compressed formats
Multiple pages: Each page adds another large image to the file

Optimal Scanner Settings

Document Type	Recommended DPI	Color Mode	Expected Size/Page
Text documents	150-200 DPI	Black & White	50-100 KB
Forms with signatures	200 DPI	Grayscale	100-200 KB
Documents with photos	200-300 DPI	Color	200-500 KB
Legal documents	200 DPI	Grayscale	100-200 KB
Receipts	150 DPI	Grayscale	50-100 KB
ID cards/Passports	300 DPI	Color	200-400 KB

Step-by-Step Compression

Upload Your Scan: Open our PDF Compressor and upload your scanned document.
Check Current Size: Note the file size - scans are often 10-50x larger than necessary.
Select Compression Level: For text-heavy scans, Medium compression works well. Use Low for documents with photos or signatures.
Use Target Size (Optional): If you need a specific size for email or uploads, set a target.
Download and Verify: Always open the compressed file to ensure text is readable.

Tips for Best Results

Scan smarter first: If possible, re-scan at lower DPI before compressing
Use document mode: Most scanners have a 'Document' mode optimized for text
Skip color when unnecessary: Grayscale saves 66% space over color
Straighten before scanning: Crooked pages don't compress as well
Clean the scanner glass: Dust and smudges create noise that increases file size
Process in batches: Our tool handles multiple files efficiently

Compression Results by Document Type

Document Type	Original Size	After Compression	Reduction
10-page text document	25 MB	1.5 MB	94%
Signed contract (5 pages)	15 MB	2 MB	87%
Tax forms with receipts	30 MB	4 MB	87%
ID scan (color)	3 MB	400 KB	87%
Multi-page form	20 MB	2 MB	90%

When Quality Matters

Legal documents: Use Low compression to preserve every detail
Medical records: Keep compression minimal for diagnostic images
Archival purposes: Consider keeping an uncompressed backup
OCR processing: Compress after OCR, not before, for best text recognition

Ready to Compress Your Scans?

Open our PDF Compressor and reduce your scanned documents to manageable sizes. All processing happens in your browser - your documents never leave your device.