MP4 to MKV converter
Convert MP4 to MKV in your browser. The streams are copied rather than re-encoded, so it finishes in seconds with no quality loss.
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Accepts .mp4 · Up to 20 files at a time · up to 667 MB each "Upload" and "download" here mean your browser reading a file from this device and writing one back to it. Nothing is sent to a server — open your browser's network panel and watch: no request carries your file.
FAQ
Is any quality lost?
None. The streams are copied into the MKV container without being decoded. Only asking for a different resolution or quality preset would force a real re-encode.
Why convert to MKV at all?
Because MKV accepts things MP4 does not: multiple audio languages, soft subtitles, chapters, attached fonts. It is the container to assemble a file in, even if you later repack it to MP4 for playback.
Will my TV play the MKV?
Often not. MKV never became part of the broadcast and mobile standards, so many televisions and hardware players do not implement it. That is the usual reason people convert the other way.
Are subtitles carried over?
Not by this conversion. MKV could hold them, but the subtitles inside an MP4 are in formats that would need converting, so they are left out. Adding subtitles to the MKV afterwards is straightforward in a tool like MKVToolNix.
How long does it take?
Seconds, because nothing is being encoded. A repack is closer to rewriting the file's index than to converting it.
Is there a size limit?
About 667 MB. A repack produces an output the same size as the input, and both have to fit in the memory the converter works in.
Is it really free?
Yes — every conversion on this site, with no account, no watermark and no daily cap. The work happens on your own device, so there is no server bill for us to pass on to you.
Do I need to install anything?
No. It runs in any modern browser, on Windows, macOS, Linux, Android and iOS. There is nothing to download and nothing to sign up for, and once the page has loaded it keeps working with the network switched off.
Related converters
- MKVtoMP4Repackages the same streams — lossless and near-instant
- MP4toMOVRepackages the same streams — lossless and near-instant
- MP4toWebMRe-encodes every frame for the new container
- MP4toAVIRe-encodes every frame for the new container
- MP4toMP3Drops the video, re-encodes the audio to MP3
- MP4toWAVDrops the video, keeps the audio losslessly as WAV
- MP4toAACDrops the video, re-encodes the audio to AAC
- MP4toFLACDrops the video, keeps the audio losslessly as FLAC