Outlook attachment limits
- Outlook.com and Outlook with internet mail accounts: 20 MB per message.
- Microsoft 365 work accounts: whatever your administrator set in Exchange. Ask IT if a 14 MB file still bounces.
- For bigger files Outlook offers a OneDrive link instead of an attachment.
Why 14 MB and not 20
Email sends attachments as text (base64), which makes them about 37% bigger. A 14 MB video becomes roughly 19 MB in the message — just under the limit, with room for the text and signature.
What fits
- About 30 seconds of 1080p or a minute of 720p video with sound.
- Several minutes of screen recording at full resolution.
The recipient’s server matters too: if it uses a smaller limit, a OneDrive or Google Drive link is the safe option for longer videos.
Questions
What is the Outlook attachment size limit?
20 MB per message for Outlook.com and internet accounts; work accounts follow the Exchange limit your company set.
Why does Outlook say my file is too large even under 20 MB?
Attachments grow by about a third when sent. Keep the video around 14 MB — this page does that automatically.
Will the recipient be able to play it?
Yes. The result is a standard MP4 (H.264 + AAC) that plays on Windows, Mac, iPhone and Android.
Last updated: 2026-10-30