Compress video for email
Gmail and Outlook.com both cap an email at 25 MB, but a video that's 24 MB on your computer won't fit: attachments are converted to text on the way out, which makes them about a third bigger. In practice the video needs to be about 18 MB. Drop it here and Wave is already set to 18 MB; it picks the bitrate the length allows, lowers the resolution if it needs to, and writes an MP4 that plays when the recipient opens it. Nothing is uploaded.
What actually changes
What a file size buys the picture
- Video
- Audio 96 kbps
- 5% kept in reserve
Pick a size and a length to see the resolution Wave would choose.
Email was designed for text, so attachments travel encoded as text (base64), which turns every 3 bytes into 4. A 20 MB video becomes about 27 MB on the way out, over the 25 MB that Gmail and Outlook.com allow per message. The limit covers the whole message, so several attachments share it. Larger files get offered as a Google Drive or OneDrive link instead. The Outlook desktop app applies 20 MB to some account types, and work accounts on Microsoft 365 can be set higher by the administrator. See Gmail and Outlook attachment size limits.
What fits in 18 MB, with Wave's 5% safety margin: a 30-second clip gets about 4,500 kbps - comfortable 1080p. A 2-minute clip gets about 1,100 kbps, which Wave encodes at 720p. A 5-minute clip gets about 450 kbps, which means 480p and only works well for talking heads and screen recordings. Past 10 minutes, a link is the better choice. The general maths is in Video bitrate explained.
Meeting recordings are the common case, and they compress well because little moves on screen. Even so, a full 30-minute meeting at 18 MB leaves under 80 kbps for picture and sound together - not enough. Trim it to the 3-5 minutes the recipient needs, which Wave does in the same panel; a 4-minute excerpt at 18 MB gets about 570 kbps, enough for clear 480p of a shared screen.
Wave's output is H.264 + AAC in MP4, which Gmail, Outlook, Apple Mail and every phone open without extra software. That matters for files from Macs and iPhones: a MOV with HEVC video may not play for a recipient on Windows, and turning on Make it play everywhere (or setting a size, which re-encodes anyway) converts it to H.264.
Three steps.
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01
Step 1
Drop the video onto Wave above. On this page the size target is already set to 18 MB.
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Step 2
Open Options to trim it to the part you need; shorter clips look much better at this size.
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Step 3
Select Convert to MP4, save the file, and attach it to your email.
Answers, specifically.
Why 18 MB when the limit is 25 MB?
Because attachments are encoded as text when the email is sent, which adds about a third to their size, and the 25 MB limit applies to the encoded message. An 18 MB video comes to about 24 MB on the way out, just inside the limit.
What are the Gmail and Outlook limits?
Gmail and Outlook.com allow 25 MB per message, counting the encoding. The Outlook desktop app limits some account types to 20 MB, and Microsoft 365 work accounts can be raised by an admin. Above the limit, both offer to send a Drive or OneDrive link instead.
Can I fit a 30-minute recording?
Not at a watchable quality: 18 MB over 30 minutes leaves under 80 kbps for picture and sound together. Trim it to the part that matters, or send a Drive or OneDrive link to the full file.
Do email services compress attachments?
No. Gmail, Outlook and the rest deliver the file exactly as you attached it, so any compression has to happen first. That's different from WhatsApp and Discord, which re-compress videos themselves.
Will the recipient be able to play it?
Yes, if it's H.264 in MP4, which is what Wave produces. That format opens in Windows, macOS, iOS and Android without anything to install.
Is my video uploaded to compress it?
No. Wave decodes and re-encodes the video in your browser, on your device. Only the email you send goes anywhere.