The limit you're working with
Gmail lets you attach up to 25 MB per message; anything larger is sent as a Google Drive link instead. Other email services set their own limits, often between 10 and 25 MB, so check the one you're sending from (and the recipient's, if you know it).
Email also encodes attachments as text (Base64), which makes them roughly a third larger in transit. Providers differ in whether they count the original or the encoded size, so leave some room: a target around 20–24 MB is safer than exactly 25 MB.
How long a video fits?
File size = bitrate × duration. 25 MB is 200 megabits, so the budget per second shrinks as the clip gets longer:
| Clip length | Average bitrate for ~24 MB | Resolution that usually looks best |
|---|---|---|
| 30 seconds | about 6 Mbps | 1080p |
| 1 minute | about 3 Mbps | 1080p |
| 2 minutes | about 1.5 Mbps | 720p |
| 3 minutes | about 1 Mbps | 720p |
| 5 minutes | about 0.6 Mbps | 480p |
| 10 minutes | about 0.3 Mbps | 480p, lower audio |
The bitrates are arithmetic; the resolution column is a rule of thumb. Fast motion (sports, handheld footage) needs more bits than a talking head, so drop one step lower for action clips.
Step by step
- Trim the clip to the part you actually need. Halving the length halves the size at the same quality.
- Open Compress video to 25 MB and choose the video. Change the target to 22 MB if you want extra headroom.
- Pick the resolution from the table above. For speech, set Audio to Lower (64 kbps) to give the picture more of the budget.
- Compress, check the Target met badge and the preview, then download and attach.
When it still doesn't fit
A long clip at 0.3 Mbps will look soft no matter how it's encoded. At that point a cloud link (Google Drive, OneDrive, iCloud) is a better way to share it, and you can still compress it first so it uploads and downloads faster.