Your PDF is 34 MB. Gmail won't attach anything over 25 MB. Outlook cuts you off at 20 MB. You could upload it to Google Drive and share a link — but the recipient expects a direct attachment, and the deadline is in 10 minutes.
The fix takes less time than writing the email itself.
Why email providers enforce size limits
Email was never designed for large file transfers. When you attach a file, the email server base64-encodes it — which inflates the actual data by roughly 33%. A 20 MB attachment becomes ~27 MB of transmitted data. Multiply that across millions of users and the bandwidth cost is enormous.
That's why every major provider sets a hard cap:
- Gmail — 25 MB per email (attachment + body combined)
- Outlook / Microsoft 365 — 20 MB default, some enterprise plans allow 150 MB
- Yahoo Mail — 25 MB
- Apple Mail (iCloud) — 20 MB, with Mail Drop for files up to 5 GB via temporary link
The practical limit for universal delivery is around 15–18 MB. Go above that and some recipients' servers may silently reject the email or strip the attachment.
How to shrink a PDF for email
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Open the PDF compress tool in your browser. No account needed — drop the file and go.
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Choose your compression level based on the target size:
- Recommended (150 DPI) — best default. Shrinks most files by 60–80% while keeping text and graphics sharp. A 34 MB file typically drops to 5–8 MB.
- Maximum (72 DPI) — for stubborn files that need to hit a strict limit. Images lose some sharpness at full zoom, but look fine at normal viewing size.
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Download the result and attach it to your email. Done.
If the file is still over the limit after Maximum compression, the document likely contains dozens of high-resolution photographs. At that point, consider splitting it: send pages 1–10 in one email and 11–20 in another, or share the full document via a cloud link and email only the executive summary.
What gets compressed (and what stays sharp)
Understanding this helps you choose the right level without guessing.
Text stays perfect. Every character, heading, and paragraph renders identically after compression. Text is stored as vector data — mathematical descriptions of shapes — and compression doesn't alter it.
Charts, diagrams, and logos stay clean. These are also vector-based in most PDFs. A 50-page financial report full of tables might shrink from 12 MB to 2 MB with zero visual difference.
Photographs lose some detail at high compression. At Recommended (150 DPI), the difference is invisible at normal viewing distances and standard print sizes. At Maximum (72 DPI), you'll notice softening if you zoom in past 200% — but for an email attachment that someone reads on a laptop, it's perfectly fine.
Scanned documents benefit most. If your PDF is a stack of scanned pages, each page is a full-resolution photograph. Compression reduces these dramatically. For even better results, run PDF OCR first — the resulting file compresses far more efficiently because actual text takes a fraction of the space that page-images do.
Quick size targets by use case
| Use case | Target size | Compression level |
|---|---|---|
| Standard email (Gmail, Outlook) | Under 15 MB | Recommended |
| Government / compliance portals | Under 10 MB | Recommended or Maximum |
| Web form upload | Under 5 MB | Maximum |
| Mobile viewing | Under 3 MB | Maximum |
For files that need to stay under 5 MB and still look professional, Recommended compression usually gets you there. Switch to Maximum only when the Recommended result is still above your target.
Frequently asked questions
What if my PDF is over 100 MB?
Break it into smaller sections first. Most PDF tools — including FILPDF — support files up to 100 MB. For larger documents, split the PDF into parts, compress each piece, then recombine if needed.
Should I compress before or after merging PDFs?
After. When you merge multiple PDFs, the process sometimes introduces duplicate fonts and redundant objects. Compressing the merged result removes that overhead in one pass, producing a smaller file than compressing each source document individually.
Will the recipient know the file was compressed?
No. The compressed PDF opens normally in every reader — Adobe Acrobat, Preview, Chrome, mobile apps. There's no watermark, no metadata tag, no visual indicator. It's just a smaller version of the same document.
Can I undo compression if I need the original quality back?
Compression is one-directional — once images are resampled to a lower DPI, the original resolution can't be recovered from the compressed file. Always keep your original file. The compressed version is for sending; the original stays in your archive.
If the file is sitting on your desktop right now, you can compress the PDF and get back to writing that email.