How it lands under the limit
A size limit is really a bit budget. A 20 MB file holds 160 million bits, and every second of the video has to share them. mp4mini spends them in this order:
- It reads the clip's length and splits the budget between sound and picture, keeping 5% spare.
- It picks the largest picture size and frame rate that budget can carry before the image breaks up.
- It encodes three short samples to see how this particular video behaves, and adjusts.
- It encodes the whole clip and weighs the result. If it is over, it goes again a little smaller, starting from the original.
You only ever get a file that is under the limit. If the tool can't get there, it says so and saves nothing.
Sizes here use 1 MB = 1,000,000 bytes, the way upload limits are usually written. That is a little stricter than counting 1 MB as 1,048,576 bytes, so a file that fits here fits there too.
When a video won't fit
Below about 250 kbps, video stops being watchable at any picture size, so mp4mini treats that as the floor. With 64 kbps of sound on top, a minute of video needs about 2.5 MB of the limit. When a clip needs more than that, the tool tells you before encoding anything, along with the longest part that would fit. You can keep that much from the start, pick a bigger limit, or remove the sound.
What fits in 20 MB
| Clip length | Starts at | Video bitrate |
|---|---|---|
| 0:15 | 1080p, 60 fps | 9.9 Mbps |
| 0:30 | 1080p, 30 fps | 4.9 Mbps |
| 1:00 | 720p, 60 fps | 2.4 Mbps |
| 2:00 | 720p, 30 fps | 1.2 Mbps |
| 3:00 | 540p, 30 fps | 0.8 Mbps |
| 5:00 | 360p, 30 fps | 0.4 Mbps |
| 8:00 | Won't fit. Up to 7:58 does. |
These are the starting points for a 1080p, 60 fps recording, such as a game clip. After the test samples, the tool may move one step up for simple footage like a screen recording, or one step down for busy footage like fast action.
Size limits of popular apps
| App | Limit | Notes | Source |
|---|---|---|---|
| Discord (free) | 20 MB | Per file. Raised from 10 MB in August 2026. | Help page |
| Discord Nitro Basic | 50 MB | Help page | |
| Discord Nitro | 1 GB | Help page | |
| Gmail | 25 MB | All attachments together. Larger files go as a Google Drive link. | Help page |
| Outlook.com | 25 MB | Larger files go as a OneDrive link. | Help page |
| WhatsApp video | 64 MB | 100 MB at 720p on fast connections, 64 MB at 480p on slow ones. | Help page |
| WhatsApp document | 2 GB | Sent as a file, so it arrives as the original. | Help page |
| Slack | 1 GB | Help page | |
| Telegram | 2 GB | 4 GB with Telegram Premium. | Help page |
Limits change. Discord raised its free limit from 10 MB to 20 MB in August 2026, so older advice to get clips under 8 MB is out of date. Each row links to the app's own help page and shows when it was last checked.
Your video stays on your device
mp4mini runs inside the browser tab. Your video is read and encoded on your own computer or phone, by the video encoder built into the browser. It is never uploaded, so there is no queue, no account and nothing to delete afterwards.
The new file carries only the picture and the sound. Location, camera model and other details stored in the original are not copied into it.
Questions
Which browsers work?
Recent versions of Chrome, Edge, Firefox and Safari, on computers and phones. Older browsers can't encode video inside a page; if yours is one of them, the tool says so.
What kind of file do I get?
An MP4 with H.264 video and AAC sound. That combination plays almost everywhere: Discord, WhatsApp, iPhone, Android, Windows and Mac.
How long does it take?
That depends on your device and the video. Longer and sharper clips take longer, and phones are slower than laptops. The tool shows the time left while it works, and you can cancel at any point.
Is there a watermark or a daily cap?
No watermark, no sign-up and no cap. The only limit on very large videos is your device's memory.
Can I cut the video too?
Yes. Trim keeps just the part you want. When a video is too long for the limit, the tool offers to keep the longest part that fits.