How to convert MP4 to MKV
- Add your .MP4 file - drop it in the box above or click to browse.
- Convert it to .MKV in a few seconds.
- Download your new .MKV file.
What to expect
- Remuxing with MKVToolNix or FFmpeg (
-c copy) is lossless - quality is unchanged and file size differs by under 1%. - HandBrake always re-encodes, which reduces quality and takes much longer; avoid it for a simple container swap.
- MKV is not universally supported - some smart TVs and phones that play
MP4may not acceptMKV, so test before deleting the original.
Frequently asked questions
Does converting MP4 to MKV reduce quality?
No, not when remuxing with MKVToolNix or FFmpeg
-c copy; the encoded data is copied byte-for-byte. Only HandBrake reduces quality because it re-encodes.Why is the MKV almost the same size as my MP4?
Because the video and audio data is identical - only the container wrapper changed. A small size difference (under 1%) comes from MKV header overhead.
Can I add subtitles during the conversion?
Yes - in MKVToolNix, add your
MP4 and subtitle file (.srt, .ass, etc.) together before multiplexing. FFmpeg also accepts multiple inputs in a single command.Will MKV play on my TV or phone?
MKV is widely supported on desktop players like VLC and many smart TVs, but not universally. Test playback before deleting your original
MP4.Programs that convert MP4: Miro Video Converter · HandBrake · Any Video Converter FREE · AviDemux · ConvertXtoDVD · Free Studio · Freemake Video Converter · MediaCoder
