Email attachment too large: Gmail and Outlook limits
Every email service caps attachments, and the limits differ even between versions of the same app. Here's what they are and how to send big files.
Updated October 2, 2026
The limits
| Service | Limit |
|---|---|
| Gmail (personal) | 25 MB for all attachments in one email |
| Outlook.com on the web | 25 MB per file |
| Outlook desktop app with Outlook.com, Gmail or other internet accounts | 20 MB in total |
| Microsoft 365 work accounts | 35 MB per message by default (your admin can change it) |
Why the limit is smaller than it looks
Email encodes attachments as text, which makes them about a third bigger in transit. That's why Microsoft's limits count the whole message including encoding, and why a file that's just under the limit can still bounce.
Shrink the file
- Videos: compress to under 20 MB. Short clips stay sharp; for longer ones, a lower resolution looks better than a very low bitrate.
- PDFs: most of the size is usually scanned pages or photos. Recompressing those images often cuts a PDF by 70 to 90%, with text left sharp.
- Photos: a phone photo is often 3 to 8 MB. Compressing to JPG or WebP at good quality usually brings it under 1 MB with no visible change.
Compress a PDF to under 20 MB, on your device
Compress PDF for emailOr send a link instead
Over the limit, Gmail swaps the attachment for a Google Drive link automatically, and Outlook can attach a OneDrive link. Links work for any size, but the recipient needs access to the file, and some company mail systems block them.
Compress a video to fit any email
Compress video for email