Split PDF by Size: Step-by-Step

Step 1: Choose the size limit

Pick Gmail 25 MB or Outlook 20 MB presets, or set a custom size for stricter systems.

If you want extra margin, target a few MB lower than the official limit.

Step 2: Upload and split

Upload the PDF and select Split by size mode. PDFThin keeps page order and creates parts that fit your limit.

You receive a ZIP file with each part named in sequence.

Step 3: Download and check

Download the ZIP and verify the parts are under the target size.

If needed, lower the target size and split again for stricter systems.

Step 4: Send the parts

Attach the parts in order and mention how many parts are included.

Recipients can read the parts sequentially or combine them later.

Does splitting change page order?

No. Parts keep the original page order and are labeled in sequence.

How many parts will I get?

It depends on file size and target limit. Larger files create more parts.

Can I split a scanned PDF?

Yes. Split-by-size works for scanned PDFs and keeps images intact.

Keep attachments clear

Include a short note in the email explaining that the PDF is split by size.

This reduces confusion and helps recipients keep files in order.

Prefer ZIP or parts

ZIPs are convenient, but some mail systems block them. If that happens, attach the PDF parts directly.

Both options keep your files under the same size target.

All PDF tools

Browse every PDFThin tool in one place.

Email-ready compression

Shrink PDFs to Gmail/Outlook limits with quality control.

Split by size

Split large PDFs into size-safe parts.

Organize PDF

Merge, rotate, delete, reorder, and split pages.

All PDF guides

Browse every step-by-step PDF guide.

Compress PDF for email (complete)

Step-by-step workflow for Gmail 25MB and Outlook 20MB limits.

Reduce scanned PDF size

Keep text readable while shrinking scanned documents.

Split PDF by size

Create parts that stay under a target MB limit.

Rotate PDF pages online

Fix page orientation for sideways scans or photos.