Email attachment size limits
Gmail allows 25 MB of attachments per message, Outlook.com 20 MB and Yahoo Mail 25 MB. Why a file under the limit can still bounce, and how to fix it.
Last updated
In short: Gmail and Yahoo Mail accept up to 25 MB of attachments per message, and Outlook.com up to 20 MB. Work and school accounts are set by an administrator and are often 10 to 25 MB. The limit covers all attachments in the message together.
Email attachments at a glance
| Gmail | 25 MB per message; larger files become a Google Drive link |
|---|---|
| Outlook.com | 20 MB per message; larger files become a OneDrive link |
| Yahoo Mail | 25 MB per message |
| Work and school accounts | Set by the administrator, commonly 10 to 25 MB |
Last checked against Email attachments's own documentation on . Limits change; if something here is out of date, the tool will still tell you exactly what your file is.
Why a 20 MB file can still bounce
Email sends attachments as text, using an encoding that makes them about a third bigger on the way. Providers state their limits allowing for that, but a mail server between you and the recipient may apply its own, lower, limit to the encoded size. Aiming a few megabytes under is what makes an attachment reliable.
Making a file fit
Photos: convert to JPG and compress. A phone photo becomes a few hundred kilobytes with no visible change.
Videos: compress to 20 MB. That is two minutes or so of 720p.
Several files: they count together, so compress each rather than zipping them. A zip barely shrinks photos or video.
Questions
What is the maximum attachment size in Gmail?
25 MB per message, counting every attachment.
What is the attachment limit in Outlook?
20 MB on Outlook.com. Work accounts on Microsoft 365 are set by the organisation.