Compressing
How to Compress a PDF for an Email Attachment
Get a PDF under the 25 MB email limit — or the 10 MB one your recipient never mentioned. Practical targets and what to do when compression is not enough.
The bounce message arrives a minute after you thought the email had gone. Attachment limits are the most common reason anyone compresses a PDF at all.
What the limits actually are
| Service | Limit |
|---|---|
| Gmail | 25 MB |
| Outlook.com | 20–25 MB |
| Yahoo Mail | 25 MB |
| Corporate Exchange servers | Often 10 MB, sometimes less |
| Government and legal portals | Frequently 5–10 MB |
Getting under the line
- 1Compress the PDF at a moderate setting first.
- 2Check the size and the readability at 100% zoom.
- 3If still over, step up the compression once.
- 4If still over, remove pages the recipient does not need — this is often the real answer.
- 5If still over, split into parts or send a link instead.
Send less rather than compressing harder
People compress a 90-page pack into illegibility when the recipient asked for one section. Extracting the pages they need produces a small, readable file and a better answer to their question. It is worth asking yourself what they actually requested before you reach for a heavier setting.
When compression is not enough
- Share a cloud link — no size limit and the recipient always has the current version.
- Split into numbered parts, clearly labelled, and say how many there are.
- Send the section that was asked for rather than the whole pack.
- Ask whether they can accept a link; most people can, and most people prefer it.
A note on confidential attachments
If the document is sensitive, compressing it in a tool that uploads means sending it to a third party in order to email it to one person. Browser-based compression avoids that entirely — the file never leaves your machine on the way to being made smaller.
Do it now
Compress PDF
Reduce file size while maintaining quality. It runs in this browser tab — your file is not uploaded anywhere.
Open Compress PDFFrequently asked questions
What size should a PDF be for email?+
Under 10 MB is safe almost everywhere. Under 25 MB works for consumer mail but not for many corporate servers.
Why was my 24 MB attachment rejected by a 25 MB limit?+
Encoding for transmission inflates attachments by roughly a third, and the limit applies after that.
Is a cloud link better than an attachment?+
Usually — no size limit, and the recipient sees the current version. Attachments are better when the recipient must keep a fixed copy.
Can I zip a PDF to make it smaller?+
Barely. A PDF is already compressed internally; zipping typically saves a percent or two and adds a step for the recipient.