MKV to MP4
Move a Matroska file into a container that phones and browsers will play.
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or drag it here
An MKV or WebM file
- Takes
- MKV files holding H.264, HEVC, VP9, or AV1 video. ProRes and other editing codecs are read but cannot be rewrapped into MP4 — they are refused by name rather than half-converted.
- Size
- Effectively unbounded, because no frame is ever decoded: the compressed packets are read off disk and written straight into the new container. Measured here, a 6 MB clip converted in about 10 milliseconds, and the cost scales with file size rather than with length or resolution.
Your file never leaves your browser during processing
How it works
To convert an MKV to MP4, drop the file onto this page — the video and audio are copied into the new container without being re-encoded, so nothing is lost and it takes seconds. Everything runs in your browser and nothing is uploaded.
MKV is a container, not a video format. A Matroska file holds the same H.264, HEVC, VP9, or AV1 video that an MP4 would; what it adds is a more flexible wrapper that can carry several audio tracks, subtitle tracks, and chapters at once. That flexibility is exactly why so little plays it: Safari will not, iOS will not, most smart TVs will not, and no browser plays it natively. Nothing is wrong with the video inside — only with the box it came in.
So this page opens the box. The compressed video and audio packets are read out of the Matroska container and written into an MP4 one, with no decoding and no re-encoding anywhere in the path. The result is bit-for-bit the same video, at the same resolution and bitrate, in a file that plays on a phone. It takes seconds rather than the many minutes a re-encode of the same file would, and the time depends on file size rather than on length or resolution.
There are no settings, because there is nothing to decide. Quality, resolution, and length all come from the source and none of them are being touched — offering a quality slider would imply a choice that is not being made. If what you want is a smaller file rather than a more compatible one, that is a re-encode, and the video compressor does it and says what it costs.
Two limits are checked against your actual file rather than assumed. An MKV can carry codecs an MP4 cannot — a file with Vorbis or FLAC audio, for instance, will have its video converted and that audio left behind, which the page tells you before you commit. And an MP4 holds one video and one audio track, so a Matroska file with several audio languages keeps the first; if you need a different one, that has to be selected before the file gets here.
FAQ
Does converting MKV to MP4 lose quality?
Not here. The video and audio streams are copied into the new container without being decoded, so what you download holds exactly the data that went in. Tools that re-encode cost a generation of quality; this one has no encoder in the path.
Why does my MKV not play on my phone or TV?
Because of the container, not the video. Matroska is not supported by Safari, iOS, or most TVs, even though the H.264 inside it is supported by all of them. Rewrapping it as MP4 is usually all that is needed.
How long does it take?
Seconds for most files, because nothing is decoded — the cost is reading and rewriting packets. A re-encode of the same file would take roughly as long as the video is.
What happens to subtitles and extra audio tracks?
They are not carried across. An MP4 keeps one video and one audio track, so the first audio track is kept and subtitle tracks are dropped. If you need a specific language, select it before converting.
Why was my MKV refused?
Because the video codec inside it cannot legally be stored in an MP4 — some MKVs carry codecs MP4 has no provision for. The page names the codec. Those files can only be converted by re-encoding, which the compressor will do.
Is my file uploaded?
No. The conversion runs entirely in your browser, and the network counter under the tool stays at zero bytes sent while your file is processed. There is no server, and so no size limit.
How large an MKV can I convert?
Effectively any size. The file is read off disk in pieces and no frame is ever decoded, so a multi-gigabyte film costs memory proportional to nothing much at all.