Choose your MP4 file
Select MP4 from your device. The file is processed locally.
ON YOUR DEVICE
MP4 to MKV
Convert MP4 videos to MKV on your device. Choose settings and download the result.
Drop your file here
One file · Device-dependent capacity · Best for short clips
Files stay on your device
Three simple steps
Prepare MKV output
MKV output uses H.264 video and AAC audio. Browser playback may be unavailable, so use a compatible desktop player.
Save and check your MKV file
The video is re-encoded. Extra audio tracks, subtitles, chapters, HDR metadata and DRM protection are not preserved or bypassed.
Common questions
What changes when I convert MP4 to MKV?
MP4 output uses H.264 video and AAC audio for broad player support. MKV output uses H.264 video and AAC audio. Browser playback may be unavailable, so use a compatible desktop player. The video is re-encoded. Extra audio tracks, subtitles, chapters, HDR metadata and DRM protection are not preserved or bypassed.
Will the MKV file be smaller?
Not necessarily. MKV output uses H.264 video and AAC audio. Browser playback may be unavailable, so use a compatible desktop player. Size depends on the source and settings. The result reports file sizes and processing time.
Which MP4 files work here?
The container must contain decodable media. Encrypted or DRM-protected streams are unsupported. Test a short sample if your recording uses an unusual codec.
Is there a size cap for MP4 to MKV?
There is no fixed file-size quota. Process one main file at a time. Your device memory and browser determine practical capacity. Large selections show a warning that you can continue past.