Compress Video for Email Attachments

Compress video for email, step by step

1. Choose the video above: MP4, MOV, M4V, WebM or MKV. iPhone videos copied to a computer are usually MOV, which is fine.
2. Pick 18 MB for Gmail, Outlook.com or Yahoo, 9 MB for a work account with a 10 MB limit, or 4 MB for a strict server. You can also type any size into "Or a size in MB".
3. Read the plan readout: it shows the resolution, bitrate and expected size, and warns when the target is too small for the video's length.
4. Press "Compress video" and keep the tab open until the download appears.
5. Download the MP4 and attach it to your message. If the result card says the file came out over the target, press "Try again 20% smaller" before attaching it.

Email attachment limits by provider

These figures come from each provider's own help pages, checked in October 2026:

Gmail, personal account

25 MB for all attachments together; anything larger is replaced by a Google Drive link automatically

Google Workspace

25 MB on Business, Education and Enterprise Standard, up to 50 MB on Enterprise Plus in web Gmail; administrators set the limits for work and school accounts

Outlook.com

25 MB, according to Microsoft's Outlook.com sending limits page

Outlook app with an internet account such as Outlook.com or Gmail

20 MB, counting the message as well as the attachment

Outlook app with an Exchange (business) account

10 MB by default, counting the message too; the IT administrator can change it

Yahoo Mail

25 MB for all attachments in one message, sent or received

Microsoft's own pages disagree on Outlook.com: the Outlook.com limits page gives 25 MB, while the article about the Outlook app gives 20 MB for internet accounts, Outlook.com included. If you send from the Outlook app, expect the 20 MB figure.

Why the preset is 18 MB, not 25

Email was built to carry text. Before an attachment travels it is converted to Base64, which turns every 3 bytes into 4 characters, so the file grows by a third, and line breaks and message headers add a little more. An 18 MB video therefore travels as roughly 24 to 25 MB.

Google says its sending limits are measured before that encoding, so Gmail itself would let a bigger file out. The trouble is the other end: the recipient's mail server may measure the encoded message, and that's where a 23 MB attachment bounces. 18 MB keeps the encoded message under 25 MB and the file itself under the Outlook app's 20 MB, so it fits all the consumer services in the table.

The 9 MB preset clears Outlook's own check on an Exchange account with the default 10 MB limit. If the company's server counts the encoded size, even 9 MB can bounce; type 7 into the size box and try again. The 4 MB preset is for mailing lists, older servers and recipients whose limits you don't know.

When a link works better than an attachment

A size cap is really a cap on minutes. Five minutes squeezed into 18 MB ends up at 360p, and a half-hour recording won't fit at any watchable quality. For anything long, send a link:

• Gmail does it for you: attach a file over 25 MB and it is put in Google Drive and added to the email as a link.
• Outlook can attach a file from OneDrive as a link instead of a copy.
• Yahoo Mail can insert a share link from Google Drive or Dropbox.

A link keeps the original quality, but the recipient needs permission to open it, and the file stays in your cloud storage until you delete it.

Making room before you compress

• Cut what the recipient doesn't need. Every second removed with trim video hands its share of the budget to the rest, and fast mode copies the part you keep without re-encoding.
• If only the voice matters, such as a recorded message or a lecture, send audio. Video to MP3 takes a few seconds, and the audio compressor can shrink a spoken recording to a small fraction of the video's size.
• For the general mechanics of size-based compression, including why the resolution drops, see the main video compressor.

How the compression runs

The video is read and re-encoded in your browser tab, and the MP4 is saved from there; nothing is uploaded. Re-encoding uses the browser's WebCodecs encoder, so it needs current Chrome or Edge, Safari 16.4 or later, or Firefox 130 or later on a computer, and the time it takes depends on the computer and the clip. The result is an MP4 with H.264 video where the browser can encode it, which mail apps on phones and computers open without extra software.

If the people you're emailing may watch without sound, captions help. The subtitle generator writes subtitles from the speech for 1 credit per minute with a 5-credit minimum, so a 3-minute clip costs 5 credits (0.5¢); for that AI step only the audio track is uploaded. Burn the subtitles into the video first, then compress the rendered file for email.