Why scanned PDFs are large
A scanned PDF often stores each page as a full-page image, so size grows quickly across long documents.
If the scan was saved at high resolution or with unnecessary color depth, the output can become much larger than needed for review or filing.
Protect what matters during compression
You usually need readable text, visible stamps, and clean page edges.
If the file will later go through OCR or Word conversion, avoid over-compressing to the point that letter shapes and page contrast degrade.
Best practice for scanned submissions
Compress once for delivery, keep the original for backup, and add OCR only if you need searchable or editable text later.
If the file still remains too large after a reasonable pass, split the bundle or re-export the scan source with better settings instead of crushing quality further.
Frequently asked questions
Why are scanned PDFs so large?
Scanned pages are stored as images, so high resolution, color depth, and long page counts can create very large files.
Can compression make scanned text unreadable?
Aggressive compression can damage fine letter shapes. Review small text and stamps after processing.
Should I use OCR on scanned PDFs?
Use OCR when you need searchable or selectable text. Keep scan quality high enough for reliable recognition.
Can I archive scanned PDFs?
Yes. After checking readability, create a PDF/A copy when an archive-oriented format is required.