Compress video for Outlook
Free, no watermark, no signup, and your file never leaves your device.
Fits Gmail/Outlook (accounts for attachment overhead)
Outlook's attachment limit is not one number, and that trips people up. Desktop Outlook (the app) defaults to 20 MB, Outlook.com on the web allows 25 MB, and business mailboxes vary: cloud Microsoft 365 accounts typically start around 35 MB and can be raised, while older on-premises Exchange can be capped as low as 10 MB by an administrator. Whichever applies to you, a phone or camera video clears it in seconds of footage, which is why "the attachment size exceeds the allowable limit" is one of Outlook's most common errors.
There is a catch that makes the real limit lower than the number suggests. Email cannot send raw files: it re-packages attachments into text using Base64 encoding, which inflates them by about a third. So an 18 MB video becomes roughly 24 MB in transit and bounces against a 20 MB cap. The practical safe size for desktop Outlook is closer to 14 to 15 MB. This tool's Email preset targets a size with that overhead already accounted for.
Everything runs on your device. For work video especially, that matters: the file is never uploaded to a third-party server, so there is no data-handling question to answer before you send it. And if your clip genuinely cannot fit at watchable quality, the honest answer is a OneDrive or Drive link rather than an attachment, which the FAQ covers.
Questions people ask
- What is Outlook's attachment size limit?
- It depends on your account. Desktop Outlook defaults to 20 MB, Outlook.com on the web is 25 MB, and business mailboxes vary (cloud Microsoft 365 typically starts around 35 MB; older on-premises Exchange can be as low as 10 MB). The limit covers the whole message, not just the file, so signatures and inline images count too.
- Why did my attachment bounce even though it was under the limit?
- Email encodes attachments in Base64, which adds about 33% to their size in transit. An 18 MB file becomes roughly 24 MB and exceeds a 20 MB cap. Aim for 14 to 15 MB on desktop Outlook, or about 18 MB on Outlook.com. The Email preset does this math for you.
- The recipient's server rejected it, not mine. Why?
- Email has to pass both your limit and the recipient's, and the smaller of the two wins. You might send 20 MB successfully, but if their server caps at 10 MB it bounces on their end. Compressing smaller gives the message a better chance of clearing both.
- When should I use a OneDrive link instead?
- For anything past a few minutes of footage, compressing to Outlook's limit costs real quality. A OneDrive or Google Drive share link preserves the original and avoids the bounce entirely. Attachments win for short clips the recipient should keep a copy of.
Platform limits last verified June 2026. Source: Microsoft Learn (Exchange Online limits) + cross-referenced sources. Limits change; if a number looks off, tell us and we'll recheck.