The size limits you will run into
| Where it is going | Typical limit | Preset to use |
|---|---|---|
| WhatsApp, sent as a normal video | About 16 MB | 16 MB |
| WhatsApp, sent as a document | Up to 2 GB, but no preview in the chat | Not needed |
| Gmail attachment | 25 MB (larger files become a Google Drive link) | 25 MB |
| Job portals, college and exam forms | Varies: check the form | Type the exact number |
Type any size into the box: a bare number like 10 means 10 MB, and KB works too. The tool treats 1 MB as 1,000,000 bytes, the smaller of the two common definitions, so a result that is "at most 16 MB" passes whichever way a website counts. The exact byte count is shown with the result.
How fitting a video to a size works
A video's size is its bit rate multiplied by its length. So the tool divides your target by the length of the video to get a budget per second, sets some aside for the sound, and gives the rest to the picture. Longer videos get fewer bits per second, which is why a 30-second clip fits into 16 MB comfortably while a 10-minute one struggles.
Squeezing a full 1080p picture into a small budget makes it blocky. With Resolution on Automatic, the tool instead picks the sharpest resolution the budget can support, never above 1080p. A 3-minute video in 16 MB, for example, has room for about 570 kbps of picture, which gives a clean 480p video rather than a smeared 1080p one. Videos filmed at 60 frames per second are brought down to 30 in this mode, so each frame gets twice the detail.
There is a floor: below roughly 0.6 MB per minute of video with sound (about 0.3 MB without), nothing watchable remains. If your target is under that, the tool tells you the smallest size that can work.
Quality level mode
If you do not have a hard limit, choose Quality level instead. High quality looks the same as the original to most eyes and is often a third to half the size of a phone video; Balanced is softer in fast movement and much smaller; Smallest is visibly softer. The file size depends on the video, so it is not known in advance, but the tool shows the size before and after. In this mode the resolution stays as it was unless you choose 1080p, 720p or 480p.
Getting the best result
- Trim first. Every second you cut is budget the rest of the video gets. The video trimmer can do a fast cut in seconds.
- Use 720p for phones. A phone screen shows little difference between 720p and 1080p, and 720p has less than half the pixels to pay for.
- Drop the sound if it is not needed. Switch off "Keep the sound" and the picture gets that space too.
- Use a computer for long videos. It will be much quicker than a phone.
The result is always MP4 with H.264 picture and AAC sound, which plays on iPhone, Android, Windows, Mac and in WhatsApp. Location and other details stored by your phone are not copied. Need a document smaller as well? The PDF compressor works the same way.
The engine behind this tool
Video and sound are processed by FFmpeg, the open-source engine behind most of the world's video software, compiled to run inside your browser as ffmpeg.wasm. It is downloaded from this site (about 31 MB) the first time you use a video or audio tool, and your browser keeps it for next time. FFmpeg and ffmpeg.wasm are free software, licensed under the GNU General Public License version 2 or later; their source code is at github.com/ffmpegwasm/ffmpeg.wasm.