Convert MP4 to WebM

How to convert MP4 to WebM

1. Drop up to five MP4 files into the box above, or click it to pick them.
2. WebM is already selected as the output format.
3. Click the button. The video engine downloads once, then every file is re-encoded on your own device.
4. Download each WebM file, or take them all as a ZIP.

Frequently asked questions

Why convert MP4 to WebM?

MP4 is what almost everything records to and almost everything can open. WebM is the open format the web was given. It is usually smaller than MP4 at the same quality, it needs no licence, and every current browser plays it without help.

Will the quality drop?

Converting re-encodes the video, and every re-encode costs a little. On ordinary footage the difference is hard to see. It shows up first in fast motion and in flat areas of colour, and it compounds if you convert the same file over and over, so convert from the original rather than from a copy of a copy.

How long does it take?

As long as your own machine needs. The engine downloads once, about 31 MB, and is then cached. After that a short clip takes seconds and a long one takes minutes, because the work happens on your processor rather than on a server queue you are waiting in line for.

Will the file get bigger or smaller?

It depends on what the original was carrying. A MP4 file that was already efficiently encoded usually comes out around the same size. One that was not, which is common with recordings straight off a device, usually comes out smaller. If size is the point, the compress tool is the one to use.

What happens to the sound?

It comes across with the video and is re-encoded alongside it. If you want the sound on its own, the extract audio tool pulls it out as MP3 or WAV, and if you want it gone, the mute tool drops it without touching the picture.

Can I convert several at once?

Yes, up to five files at a time, up to 200 MB each. They are converted one after another on your device and you can download them individually or all together as a ZIP.

Is anything uploaded?

No. The converter is a video engine compiled to WebAssembly that runs inside the page, so your files are read by your own browser and never leave the device. That is also why it works with no account and no upload limit beyond what your machine can hold.

Is it really free?

Yes. No sign-up, no trial, no watermark and no cap on how many videos you convert. The site is paid for by ads.

Other files you can turn into WebM

The same file, something else

More free tools: Convert · Trim · Compress · To GIF · Extract audio · Mute · Resize