Reference · Updated July 2026

Outlook attachment size limit for video

Outlook has three different limits depending on how you use it: 25 MB on Outlook.com and the web app, 20 MB in the classic desktop app, and 35 MB by default on Microsoft 365 work and school accounts. All of them are measured after email encoding, which adds about a third — so a video needs to be roughly two-thirds of the stated limit to actually send.

Outlook attachment limits at a glance

Verified against official documentation · July 2026
What	Limit
Personal accounts	25 MB web · 20 MB desktop app
Work and school accounts	Microsoft 365 work accounts default to 35 MB (raised from 25 MB in 2026). Attaching from OneDrive allows up to 2 GB as a link.
Fits in practice	Roughly two-thirds of the limit that applies to you — about 16 MB on the web, 13 MB in the desktop app and 23 MB on a default Microsoft 365 account — because attachment encoding adds about a third on the wire.

The desktop app is the one that surprises people: its 20 MB applies to the whole encoded message, so a 16 MB video that sent fine from the web is rejected from the app on the same account. Company administrators can also set their own limits, higher or lower than the defaults, so a bounce on a work account may not match any number here.

Get your video under your Outlook limit

Drop the video below and pick the target that matches how you send: 16 MB is safe for Outlook.com and the web app, and for the desktop app choose a custom target of 13 MB. On a default Microsoft 365 account, 25 MB fits. Compression runs on your own device — nothing is uploaded — and the result is checked so it never lands over your target.

This compressor runs entirely in your browser and needs JavaScript to access your video file locally. Enable JavaScript to use it — your video still won't be uploaded anywhere.

How much video fits in an Outlook attachment?

With about 16 MB to work with on the web, length decides the picture size. These rows are what this compressor actually produces from a typical phone recording — full HD, 30 frames a second, with sound — at a 16 MB target.

What 16 MB gives you at different video lengths
Video length	What you get
30 seconds	Full HD — hard to tell from the original
1 minute	Nearly full HD, still sharp
3 minutes	Reduced size — fine on a phone, soft on a laptop
10 minutes	Small picture; watchable, blocky on a big screen

Past about 22 minutes, 16 MB stops being enough for a picture worth watching; at the desktop app's 13 MB the ceiling is a little lower. For a long video at good quality, attach it from OneDrive as a link — Outlook allows up to 2 GB that way — or let the compressor keep the opening stretch that fits, which it offers when a clip is too long.

Attachment or OneDrive link?

Outlook offers to upload large files to OneDrive and send a link instead; the recipient downloads from there. That gets around the limit but adds a click, counts against your OneDrive storage and depends on sharing permissions working across organisations. A real attachment lands in the inbox and plays from the message on most phones, so it is worth getting a video under the limit when you can.

Everything on this page runs locally in your browser — your video never leaves your device and nothing is stored anywhere. Not sure a clip will fit at a decent quality? The bitrate calculator tells you the picture size a given target supports for your video's exact length before you start.

Frequently asked questions

Why does Outlook reject a video that's under 25 MB?

Two usual reasons. The limit is checked after email encoding, which adds about a third, so a 20 MB video becomes roughly 27 MB on the wire. And the classic desktop app has its own 20 MB limit on the whole message, lower than the web app's 25 MB. A video around 16 MB or less sends from the web; 13 MB or less from the desktop app.

What is the attachment limit on a Microsoft 365 work account?

35 MB by default, raised from 25 MB in 2026 — but administrators can set it anywhere from a few megabytes to 150 MB, so your organisation's limit may differ. If a work send bounces, the bounce message states the limit that applied.

How do I send a video over the Outlook limit?

Either compress it under the limit with the tool above, which keeps it as a real attachment, or attach it from OneDrive as a link — Outlook allows files up to 2 GB that way, and the recipient downloads it.

Is the limit per attachment or per message?

Per message: all attachments together, plus the message body, after encoding. Two 12 MB videos in one email will bounce from an account with a 25 MB limit even though each is under it.

Is my video uploaded when I compress it here?

No. Compression runs in your browser on your own device — there is no server, no account and no watermark. The only upload that happens is the one you make when you attach the finished file to your email.