Convert MP4 to MKV

How it works

1. 1

   Add your MP4 file

   Drop, pick, or paste it. It stays on your device.

2. 2

   Convert

   We re-encode it to MKV right here in your browser.

3. 3

   Download

   Save the MKV file.

The container you choose when you are archiving

MKV exists because MP4 is a slightly conservative format. MKV will carry several audio tracks in one file, so a film can hold its original language and a dub together. It will carry proper subtitle tracks that can be switched on and off. It will hold chapters. MP4 handles some of that awkwardly and the rest not at all.

That makes MKV the natural home for a video you intend to keep, catalogue, and watch on your own equipment, which is why media libraries and home servers are full of them. The streams from your MP4 move across untouched, so the conversion is a rewrap and no quality is lost.

It is also why an MKV is useless for sharing. Websites will not take one, most phones will not open one, and a good deal of software refuses the container outright. Convert to MKV for your shelf, not for anybody's inbox.

Why nothing uploads

Other tools send your video to their servers, which costs them money per file, so they add watermarks, cap file sizes, and make you sign up. This tool does the work right here in your browser using your own device. Your file is never uploaded, so there is no wait, no watermark, no size limit, and no account.

Questions

Why convert away from MP4 at all?

For multiple audio tracks, switchable subtitles, or chapters, all of which MKV supports properly and MP4 does not.

Does this lose quality?

No. The streams are copied into the new container rather than decoded, so the video is bit for bit what it was.

Can I upload an MKV anywhere?

Realistically, no. Almost every platform refuses the container. Keep the MP4 for sharing and use the MKV for storage.

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