Trying to email a PDF but getting "attachment too large" errors? Most email providers limit attachments to 10-25MB, and many corporate mail servers are even stricter. Here's how to compress any PDF to email-friendly size.
Why PDFs Get So Large
Before compressing, it helps to understand what makes PDFs large:
- High-resolution images - A single photo can be 5-10MB
- Embedded fonts - Each font adds 100-500KB
- Scanned documents - Scans are images, not text
- Multiple pages - More pages = more size
- No compression applied - Many PDF creators don't optimize
The Fastest Method: Online Compression
Step-by-Step:
- Go to lexosign.com/compress-pdf
- Upload your PDF (drag & drop or click)
- Select compression level:
- Light - Minimal quality loss, smaller reduction
- Medium - Balanced (recommended for most)
- Strong - Maximum compression, some quality loss
- Click Compress
- Download your smaller file
Typical Results:
- 20MB file → Under 2MB with medium compression
- 50MB scan → Under 5MB with strong compression
Compression Level Guide
When to Use Light Compression
- Documents that will be printed
- Files with diagrams or technical drawings
- When you only need slight size reduction
Expected reduction: 20-40%
When to Use Medium Compression (Recommended)
- Most email attachments
- Documents viewed on screen
- Reports with photos and text
Expected reduction: 50-70%
When to Use Strong Compression
- Email attachments with strict limits
- Archive copies you rarely access
- Quick previews or drafts
Expected reduction: 70-90%
Warning: Strong compression can make photos look pixelated. Always preview before sending.
What If It's Still Too Large?
Option 1: Split the PDF
If compression alone doesn't work, split the document:
- Split your PDF into smaller parts
- Compress each part
- Send as multiple emails or use cloud storage
Option 2: Convert Scans to Searchable PDF
Scanned documents are especially large. Converting to searchable PDF (OCR) can reduce size while making text searchable:
- Run OCR on your PDF
- The OCR process often reduces file size
- Bonus: You can now search and copy text
Option 3: Use Cloud Storage
For very large files, upload to cloud storage and share a link:
- Google Drive (15GB free)
- Dropbox (2GB free)
- OneDrive (5GB free)
This bypasses email attachment limits entirely.
Tips for Smaller PDFs from the Start
Creating from Word/Google Docs
When exporting to PDF:
- Resize images before inserting (don't paste giant photos)
- Use "Minimum size" option if available
- Avoid unnecessary embedded fonts
Scanning Documents
- Scan at 150 DPI for screen viewing (not 300 or 600)
- Use black & white for text-only documents
- Scan directly to PDF, not image files
After Creating
- Remove blank pages
- Delete unnecessary attachments or comments
- Run compression as a final step
Common Compression Mistakes
Compressing Multiple Times
Each compression cycle can degrade quality. If your first compression isn't enough, start over with stronger settings rather than re-compressing.
Wrong Compression Level
Using "Strong" on a document meant for printing will look terrible when printed. Match compression to intended use.
Not Checking the Result
Always open the compressed file and scroll through before sending. Verify text is readable and images are acceptable.
Understanding Quality vs Size Trade-offs
Here's what happens at each compression level:
| Element | Light | Medium | Strong |
|---|---|---|---|
| Text | Perfect | Perfect | Perfect |
| Line drawings | Perfect | Perfect | Good |
| Photos | Excellent | Good | Acceptable |
| Fine details | Preserved | Mostly preserved | Some loss |
Text always stays sharp because it's compressed differently than images. Photos take the biggest hit with strong compression.
Security Note
When using online compression tools:
- Check privacy policies - LexoSign deletes files after 30 minutes
- Use HTTPS - Look for the padlock icon
- Avoid unknown tools - Stick to reputable services
For highly confidential documents, use offline tools like Adobe Acrobat.
Quick Reference: Target Sizes
| Use Case | Target Size | Compression Level |
|---|---|---|
| Gmail attachment | Under 25MB | Light-Medium |
| Outlook/corporate | Under 10MB | Medium |
| Very strict limits | Under 5MB | Medium-Strong |
| Email body embed | Under 1MB | Strong |
Conclusion
Most PDFs can be compressed to email-friendly sizes in under 30 seconds using online tools. Start with medium compression, check the result, and adjust if needed.
Compress your PDF for free at LexoSign - instant results, no watermarks, files deleted after 30 minutes.
If you regularly work with large documents, consider these habits:
- Compress images before creating PDFs
- Use appropriate scan settings
- Keep a cloud storage link handy for exceptions