Y4M to MKV converter
Convert Y4M to MKV in seconds, free and unlimited. No upload, no sign-up, no watermark: your video never leaves your device.
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Quick answer: To convert Y4M to MKV, add the Y4M file to the iHateFiles Y4M to MKV converter and press Convert. The conversion runs in your browser, so the file is never uploaded, and it is free with no sign-up, watermark or size limit. Y4M is a format most software has stopped opening. MKV is not.
Should you convert Y4M to MKV?
Yes. Y4M is a format most current software no longer opens, so converting it is the reliable way to keep watching it. MKV is a reasonable target; MP4 is the safest.
The picture is re-encoded
A Y4M usually holds completely uncompressed frames with no sound. This writes H.264 video with AAC sound into the MKV. The source is uncompressed, so this is the first and only round of loss.
There is no sound to carry
A Y4M carries no audio track, so the MKV comes out silent. If the sound exists as a separate file, add it afterwards with the Replace Audio tool.
Expect a smaller MKV
H.264 video is a much more efficient codec than what a Y4M holds, so at the same visual quality the MKV is usually a third to a half of the size.
Where the MKV will play
MKV plays on VLC, Plex, most smart TVs and Android, but not the iPhone Photos app or QuickTime.
Y4M and MKV side by side
| Y4M | MKV | |
|---|---|---|
| Inside the file | completely uncompressed frames with no sound | H.264 video with AAC sound |
| Compression | Lossless | Lossy |
| Carries sound | No | Yes |
| Plays on | Needs converting first | VLC, Plex, most smart TVs and Android, but not the iPhone Photos app or QuickTime |
| Here | Read only | Read and write |
What usually goes wrong
About the Y4M. A few seconds of Y4M can be larger than a whole film in MP4. That is the format doing its job.
About the MKV. MKV and WEBM share a signature because WEBM is a restricted Matroska, so tools sometimes report one as the other. What matters is the codecs inside.
How to convert Y4M to MKV
- Add your Y4M file. It is read from your disk and stays there.
- Check the settings. The output format is already set to MKV.
- Press convert and the MKV file is saved back to your device.
Questions
How do I convert Y4M to MKV?
Open this page, add your Y4M file, and press convert. The file is decoded and re-encoded by your own browser and saved back to your device. Nothing is uploaded.
Is this Y4M to MKV converter free?
Yes, completely. There is no account, no sign-in, no watermark and no daily limit, because there is no server doing the work. Your own device does it.
Are my files uploaded anywhere?
No. There is no upload endpoint. The conversion runs inside this browser tab, so your file never leaves your device. You can open your browser's network panel and watch: nothing carrying your file is sent.
Is there a file size limit?
No fixed limit. Because the work happens on your machine there is no server quota. The only ceiling is your own device's memory, which for video means very large files may be slow.
Will converting to MKV lose quality?
MKV is a lossy format, so some detail is discarded. The quality control on this page decides how much. The default is set high enough that most people cannot see the difference.
Can I convert several Y4M files at once?
Yes. Add as many as you like and they are converted one after another, then offered as a single ZIP.