How to Compress a PDF for Email (Under 25MB)

Why Email Providers Block Large PDFs

Gmail, Outlook, and Yahoo all enforce a 25MB attachment limit. If your PDF is over that threshold, your email silently fails or bounces back. Worse, many corporate mail servers set the bar even lower — 10MB or even 5MB.

The good news: most PDFs are far larger than they need to be. Embedded fonts, bloated metadata, and unoptimized object streams can double or triple the file size without improving quality.

What Makes PDFs So Large?

A few common culprits:

• Embedded fonts — every font variant (bold, italic, light) gets bundled into the file
• Metadata bloat — author info, edit history, and application data that readers never see
• Uncompressed object streams — older PDF creators sometimes skip compression entirely
• High-resolution images — scanned documents often embed images at 300+ DPI when 150 DPI would be perfectly readable

How to Compress a PDF for Free

You can use PDFShift's Compress tool to reduce your PDF file size in seconds. Here's how it works:

1. Drop your file onto the upload area (or click to browse)
2. Wait a moment — compression happens instantly in your browser
3. Download the smaller file and attach it to your email

The entire process runs locally on your device. Your file is never uploaded to a server, so there's zero privacy risk — even for sensitive contracts, tax forms, or medical records.

How Much Smaller Will My PDF Get?

Results vary depending on the original file, but typical reductions are:

• Text-heavy documents: 20–40% smaller
• Scanned documents with images: 10–30% smaller
• Files with bloated metadata: 30–50% smaller

PDFShift strips unnecessary metadata (author, producer, creator, subject, keywords) and re-encodes object streams with modern compression. The visual content stays identical.

Tips for Even Smaller Files

If your compressed PDF is still too large for email:

• Split it first — use the Split tool to extract only the pages you need
• Send a link instead — upload to Google Drive or Dropbox and share a link
• Reduce image quality before creating the PDF — if you control the source document, export images at 150 DPI instead of 300

When Compression Isn't Enough

Some PDFs contain high-resolution photos or complex vector graphics that don't compress well. In those cases, splitting the document into smaller sections is usually the best approach. You can split your PDF by page range and send multiple smaller attachments.

Privacy Matters

Unlike online compression services that upload your file to a remote server, PDFShift processes everything in your browser using WebAssembly. Your documents never leave your device — not even temporarily. This makes it safe for:

• Legal contracts and NDAs
• Financial statements and tax returns
• Medical records and personal documents
• Confidential business reports

No account required. No file size tracking. No data collection.