Compressing PDFs to Meet Email and Upload Size Limits

You've scanned your documents, and now the upload fails with "file too large". It's one of the most common annoyances with scanned paperwork, and it's usually solvable in a minute.

Why scans are large

Each scanned page is an image, and images hold a lot of data. A multi-page colour scan at high resolution can easily reach tens of megabytes. Text-based PDFs are far smaller, since they store letters instead of pictures.

Typical size limits

Limits vary, but you'll often meet:

• Email attachments: commonly around 20 to 25 MB in total, and some workplaces set lower limits.
• Online application portals: frequently between 1 and 10 MB per file, sometimes less.
• Messaging apps: limits differ, and they may compress files further.

Always check the requirements on the form or in the instructions.

Ways to reduce size

1. Compress the PDF. Most scanning apps can reduce a PDF's size by compressing the images. Try a medium setting first, and check the text afterwards.

2. Use black and white for text pages. Switching a text-only document from colour to black and white can cut its size dramatically.

3. Reduce resolution. A scan at 150 to 200 DPI is usually enough for reading on screen.

4. Scan only what's needed. Leave out blank pages, back covers and pages the recipient doesn't need.

5. Split into parts. If a document is very long, send it as two or three files, such as "Part 1 of 3".

6. Share a link. For big files, upload to cloud storage and send a link, if the recipient accepts this.

Check quality after compressing

Zoom in on the smallest text, signatures and numbers. If they've become blurry, use a lower level of compression, or higher-quality scans of the pages that matter.

Portals with strict limits

If a form allows only 2 MB, try:

1. Scanning in black and white.
2. Reducing the number of pages.
3. Compressing at a stronger level, then checking.
4. Uploading each document as a separate file, where allowed.

Keep the master

Store the original, high-quality scan, and make a compressed copy for sending. You'll then have the best version if you ever need to print or resubmit.

Common mistakes

• Sending large files by messaging apps that compress them unpredictably.
• Compressing repeatedly, which degrades quality each time.
• Deleting the high-quality original.

Quick recipe for a 5 MB limit

1. Scan text pages in black and white.
2. Keep photos and stamps in colour only where needed.
3. Compress at a medium setting.
4. Check file size before uploading.

Compress scans for easy sharing with Document Scanner →