Scanned PDF Guide

Reduce Scanned PDF Size Online

Scanned PDFs are often much larger than normal PDFs because they contain image-based pages. If your scanned document is too large for email, job applications, school portals, or online forms, you can compress it before uploading.

By Gary·Last updated October 8, 2026

Why scanned PDFs become large

When you scan documents, each page may be saved as a high-resolution image. This can make even a short document very large, especially if it includes colour pages, photos, signatures, stamps, or multiple scans.

How to reduce scanned PDF size

1. Open the PDF compressor tool.
2. Open your scanned PDF file.
3. Wait for compression to finish.
4. Download the smaller PDF.
5. Open it and confirm the text is still readable.

Best uses for scanned PDF compression

• Immigration or visa documents
• Job application documents
• School and university uploads
• Signed forms
• Receipts and invoices
• Certificates and ID documents

How to compress without losing quality

• Scan documents clearly before converting to PDF.
• Avoid blurry phone photos.
• Do not over-compress official documents.
• Check signatures, stamps, and small text after compression.
• Use Split PDF if only some pages are required.

Documents to review carefully

Review passports, IDs, certificates, immigration forms, legal papers, receipts, invoices, and signed documents after compression. If any important detail looks blurry, use a clearer scan or split the document into smaller files.

Scan smaller in the first place

Scanner and phone settings decide most of a scan’s size. If you are about to rescan, a few choices make the file much lighter before compression even starts.

• Use greyscale or black and white for text documents; colour multiplies the size.
• Use a normal document resolution rather than the scanner’s maximum photo setting.
• Scan only the pages you need, and skip blank backs of single-sided pages.

Phone scans

A phone photo of a page is usually far larger than the page needs to be. Photograph on a flat surface in even light so the page fills the frame, then turn the photos into one PDF with Scan to PDF or JPG to PDF and compress the result.

Make scans searchable as well as smaller

Compression does not make text in a scan selectable. If you also need to search or copy the text, run OCR on the scanned PDF. OCR runs in your browser, so it is slower than compression, but the document never leaves your device.