Video format
The MKV format
MKV is a flexible container for any codec, with several audio and subtitle tracks. Matroska was released in 2002 as an open container that could hold any codec, with any number of audio and subtitle tracks.
When to use MKV
Use MKV for a media library where one file should carry every language and subtitle.
It is best for films and series with several languages and subtitle tracks, and it opens on VLC, Plex, Kodi and many smart TVs, but not iPhones, most editors or social apps.
How to open it: VLC, mpv, IINA and Plex play MKV files; QuickTime and most phone galleries don’t.
| Full name | Matroska Video |
|---|---|
| Extensions | .mkv |
| MIME type | video/x-matroska |
| Introduced | 2002 |
| Compression | Lossy |
| Usually contains | H.264 or HEVC video with AAC, AC-3 or Opus audio, often plus subtitles |
| Support | Patchy support |
| Typical size | Depends entirely on the codec inside |
Good at
- Multiple audio and subtitle tracks
- Chapters and attachments
- Holds almost any codec
Not so good at
- Phones, editors and upload forms usually reject it
The common mistake
Converting an MKV to a single-track format keeps only one audio track and drops soft subtitles unless you pick them.
Compare MKV with
Questions
What is an MKV file?
MKV (Matroska Video) is a flexible container for any codec, with several audio and subtitle tracks. Matroska was released in 2002 as an open container that could hold any codec, with any number of audio and subtitle tracks.
How do I open an MKV file?
VLC, mpv, IINA and Plex play MKV files; QuickTime and most phone galleries don’t.
How do I convert MKV to another format?
Pick the target on this page, or open the Video Converter, drop the MKV file and choose a format. It converts in your browser, so nothing is uploaded.