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
Can OCR make a scanned PDF smaller?
Not by itself. OCR helps with text recognition, not guaranteed file reduction. Size changes depend on the full workflow.
Should I compress before or after OCR?
If OCR quality matters, avoid aggressive compression first. Heavy degradation can make later recognition worse.