MKV to MP4 converter
Rewrap an MKV as MP4 so it plays on TVs, phones and consoles. Where the video stream is already compatible it is copied rather than re-encoded, which takes seconds instead of minutes.
Drop an MKV file here, or choose one
Converted on your device · nothing is uploaded · no size limit
- No upload — files stay on your device
- No signup and no watermark
- No file size limit
Most MKV files already contain H.264 video — exactly what an MP4 is supposed to hold. The video is not the problem; the container is. Smart TVs, PlayStation and Xbox consoles, older Android phones and most set-top boxes read MP4 and ignore MKV entirely.
That means the conversion is often just a rewrap: the video stream is lifted out and placed into a new container untouched, with no re-encoding and no quality loss whatsoever. When the source contains something MP4 cannot hold, the tool falls back to a full re-encode automatically.
How to convert MKV to MP4
- Choose your file. Drag an MKV file onto the strip above, or click it to browse. The first file also loads the converter itself, which takes a few seconds.
- Wait for the bar to fill. Encoding runs on your own processor. A one-minute 1080p clip usually takes under a minute; keep the tab open while it works.
- Download the MP4. The finished file appears as a download button and saves straight to your device.
Why convert MKV to MP4
No quality loss when the stream is copied
Copying moves the compressed video bit for bit. The output is visually identical to the input because it contains the same data in a different wrapper.
It finishes in seconds
A rewrap is limited by how fast your disk reads, not by how fast your processor encodes. Multi-gigabyte files often complete in under a minute.
Media servers and TVs stop refusing it
Direct playback on a TV app or console needs MP4. An MKV usually triggers server-side transcoding, which looks worse and stutters.
Audio is normalised to AAC
MKV files frequently carry DTS or AC-3, which MP4 support for is patchy. Converting the audio to AAC avoids a video that plays silently.
What survives the conversion
| Element | What happens | Result |
|---|---|---|
| Video stream | Copied unchanged where compatible | Identical quality |
| Audio | Re-encoded to AAC at 192 kbps | Near-identical |
| Subtitles | Not carried over | Extract separately if needed |
| Multiple audio tracks | First track only | MP4 handles these poorly |
| Chapters | Not preserved | — |
Doing it yourself with ffmpeg
If you convert files regularly, or need to process a whole folder, run it locally instead. This is the same operation the tool above performs:
ffmpeg -i input.mkv -c:v copy -c:a aac -movflags +faststart output.mp4Every flag is explained in the guide to the ffmpeg command.
Questions
Will my subtitles come across?
No. MKV subtitle tracks, particularly image-based formats like PGS, do not map cleanly into MP4, so they are dropped. If you need them, extract the subtitle track as an SRT file separately and load it alongside the video in your player.
Does this reduce quality?
When the video stream is copied — which is the common case — there is no quality change at all, because nothing is re-encoded. If the source uses a codec MP4 cannot carry, a full re-encode happens instead and a small amount of quality is lost.
What about a second audio track or a commentary?
Only the first audio track is kept. MP4's handling of multiple audio tracks is inconsistent across players, so keeping one avoids a file that plays the wrong language.
How large a file can I convert?
Because the conversion runs in a browser tab, memory is the constraint. Files up to about 2 GB work on a desktop. Above that, use the ffmpeg command below on your own machine — for a stream copy it takes almost no time.
Why is the size almost identical to the original?
That is the expected result of a rewrap. The video data is the same; only the container and the audio track changed.
Is anything uploaded?
No. Nothing leaves your device at any point.