Email attachment limits
| Service | Limit (reported) |
|---|---|
| Gmail | 25 MB per email |
| Outlook (Microsoft 365 desktop app, internet accounts) | 20 MB per email |
| Many company mail servers | 10 to 20 MB |
These limits come from widely reported figures and are marked unverified in the sources below; check your provider's help page. Attachments are converted to text for sending (Base64), which makes them about a third bigger, and some providers count that encoded size. An 18 MB video becomes about 24 MB in transit, which still fits Gmail.
What this preset does
It targets 18 MB, picks a resolution up to 720p (lower for long videos), keeps the sound at 96 kbps, and encodes MP4 with H.264 and AAC, the combination that plays in every email app's preview and on every phone. You see the estimated size before you start and the actual size after.
How much video fits in 18 MB
About 1.5 minutes looks good at 720p; 3 minutes at 480p is fine for talking and presentations; beyond 5 minutes, quality falls off and a cloud link is the better option. For a long recording, trim it to the part that matters first.
If the recipient's server is stricter
Some company mail servers reject attachments over 10 MB. If your email bounces, choose a custom size of 9 MB and try again, or share a link.
What decides a video's file size
A video file is mostly its bitrate (how many bits are spent per second) multiplied by its duration. A 2-minute clip at 2 megabits per second is about 2 × 120 ÷ 8 = 30 MB, plus the sound. Everything else matters only through the bitrate it needs to look good:
- Resolution. 1080p has 2.25 times the pixels of 720p, so it needs roughly twice the bitrate for the same sharpness. Below a certain bitrate, a smaller resolution looks better than a blocky big one, which is why the automatic setting steps down.
- Frame rate. 60 fps needs more bitrate than 30 fps; for talking, screen recordings and most phone clips, 30 or even 24 fps is plenty.
- Movement and detail. A static screen recording compresses far better than handheld footage of a crowd, confetti or water. Two videos of the same length and settings can differ several-fold in size.
- Codec. H.264 plays everywhere. VP9, HEVC (H.265) and AV1 give the same quality in 30 to 50% fewer bits but are not supported by every player or upload form.
- Sound. Usually small: 96 kbps stereo is about 0.7 MB a minute. Removing it helps only for very small targets.
If the email still bounces
- Check the total of all attachments, not just the video, is under the limit.
- Read the bounce message: it usually names the recipient's server and its limit.
- Send a link from OneDrive, Google Drive, Dropbox or iCloud instead; the recipient gets full quality and you avoid the limit altogether.
Making the most of 18 MB
Cut anything the recipient does not need first: long intros, the walk to the camera, the end where you reach for the stop button. Then cap the frame rate at 30 fps and, for presentations or screen recordings, choose 64 kbps sound. These three changes often let a clip stay at 720p.
Privacy
Your video never leaves your device. It is read and written in the browser tab; there is no upload, no server-side processing and no account. You can disconnect from the internet after the page has loaded and it still works. Free use has no watermark and covers files up to 500 MB and 10 minutes; the A$9 lifetime licence removes those limits (your device's memory still applies), queues up to 20 files and saves presets.