Compress a PDF for Outlook.com
Outlook.com takes PDFs up to 25 MB. PDF Desk shrinks yours to just under it, right in this tab.
Max 25 MB
Files stay on this device. Nothing is uploaded.
Outlook.com upload limits
| Document | Max size | Min size | Formats |
|---|---|---|---|
| Email attachments OneDrive file links can be up to 2 GB. | 25 MB | — |
Where this number comes from
“The attachment size limit for files is 25 MB.”
— Sending limits in Outlook.com – Microsoft Support. Checked October 2026.
PDF Desk aims at 24.3 MB, a little under the limit, because some portals count 1 KB as 1,000 bytes.
If the file will not get small enough
Scan in black and white at 150 DPI instead of colour. Remove blank and duplicate pages with Delete pages. If the portal allows several files, cut the PDF with Split PDF and upload the parts.
Other portals in Worldwide (email, messaging, global services)
Limits of other portals
Questions
What is the maximum PDF size for Outlook.com?
Email attachments: 25 MB. Source: support.microsoft.com, checked October 2026.
Outlook.com still rejects my PDF. Why?
Check that it is not password-protected, that the file name has no special characters, and that it is a few percent under the limit — some portals count 1 KB as 1,000 bytes.
Are my PDFs uploaded?
No. PDF Desk opens and writes the file with JavaScript inside your browser tab. Nothing is sent to a server, so it is safe for contracts, IDs and bank statements.