Compress video for Outlook
Getting "the attachment size exceeds the allowable limit" in Outlook is usually because desktop Outlook's default is only about 20MB — lower than Gmail. Different Outlook versions cap differently, and you can't know which one the recipient uses, so compressing under 20MB is the safest move. The tool above is preset to 20MB.
Quick answer
Outlook's attachment limit depends on the version: desktop Outlook defaults to about 20MB, Outlook.com to ~25MB, and Microsoft 365 to ~35MB (admins can change it). Compressing under 20MB is the safe bet that clears every version. ConvertMeow compresses locally in your browser — no upload, no watermark.
Shrink your video to 20MB
Target size
Derives a bitrate from target size ÷ duration and re-encodes; best for short clips.
Attachment limits across Outlook versions
Desktop Outlook (e.g. Outlook 2016–2024) defaults to about 20MB per message; web Outlook.com is about 25MB; business Microsoft 365 defaults to about 35MB, though admins can raise or lower it.
Like Gmail, this is the whole-message limit. You can't control which version the recipient uses or how strict their company mail server is — so compressing under the lowest tier (20MB) is safest.
- Desktop Outlook: ≤20MB (the safe tier).
- Outlook.com: ≤25MB.
- Microsoft 365: ~35MB default, but don't bet the recipient hasn't lowered it.
Still blurry at 20MB?
Longer videos look soft at 20MB. Trim to the segment you actually need first so the bitrate is spent on the key footage; or, if quality is critical and it must go, use a OneDrive share link and put only the link in the email.
Frequently asked questions
It depends on the version: desktop Outlook defaults to ~20MB, Outlook.com ~25MB, Microsoft 365 ~35MB (admin-configurable). Since you can't know the recipient's version, compressing under 20MB is safest.
Because the video is over your Outlook version's attachment cap (desktop defaults to only ~20MB, lower than many expect). Compress under 20MB, or use a OneDrive link instead.
No. Compression runs entirely locally in your browser with ffmpeg — never uploaded, no watermark, no cap.
Updated · ConvertMeow team