Trying to attach a PDF to an email only to get a "file too large" error is a common problem. Most email providers cap attachments at 10–25 MB. Here is how to get your PDF under that limit reliably.

Common Email Attachment Limits

| Service | Attachment limit | |---|---| | Gmail | 25 MB | | Outlook.com | 20 MB | | Yahoo Mail | 25 MB | | iCloud Mail | 20 MB |

Corporate Exchange servers often have stricter limits (5–10 MB). When in doubt, aim for under 10 MB.

Step 1: Compress the PDF

The fastest approach for most PDFs is to use ToolzStack's PDF compressor.

  1. Go to /compress/pdf
  2. Upload your PDF
  3. Download the compressed version

For a typical document with embedded images, this usually reduces file size by 30–70%. A 15 MB brochure might compress to 4–6 MB.

Step 2: If the Compressed PDF is Still Too Large

Remove or reduce images

If the PDF is image-heavy (a photo portfolio, brochure, or scanned document), the images are the primary source of size. Options:

  • Re-export from source at a lower image resolution if you have the original file
  • For scanned PDFs, re-scan at 150 DPI instead of 300 DPI if quality allows

Flatten the PDF first

Interactive PDFs (with form fields, layers, or annotations) carry extra overhead. Flatten the PDF to remove these layers, then compress the flattened version.

Remove embedded fonts

Rarely available in basic tools, but if you have Adobe Acrobat or a similar tool, removing unused embedded fonts can trim tens of kilobytes.

Step 3: If It Cannot Be Reduced Enough

Use cloud sharing instead

Upload the PDF to Google Drive, Dropbox, or OneDrive and send the recipient a link instead of an attachment. This bypasses the email limit entirely and is the standard approach for large files.

Split the document

If you are sending a large multi-chapter document, split it into logical parts using PDF Split and send each part as a separate email. Note: this only makes sense if the recipient can receive and use partial documents.

A Practical Size Guide

| PDF content | Expected size after compression | |---|---| | Text-only contract (20 pages) | Under 500 KB | | Mixed text and images (20 pages) | 1–5 MB | | Image-heavy brochure (20 pages) | 3–10 MB | | High-res scan (20 pages, 300 DPI) | 10–40 MB |

For high-res scans, cloud sharing is often the only practical option if you must preserve full resolution.

Related guides: How to Compress a PDF Without Losing Quality