MKV file format: what it is and how to use it

Matroska is the everything-container: unlimited video, audio and subtitle tracks, chapters and attachments in one open file. Learn when to use it and what to choose instead.

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What is a MKV file?

An .mkv file is media in Matroska, the open, EBML-based container designed to hold anything: multiple video and audio tracks, dozens of subtitle streams, chapters, attachments and rich metadata, all in one extensible file. Unlike MP4 it imposes no codec politics, so whatever exists can be muxed in, which made it the container of choice for rips, remuxes and archives.

When should you use MKV?

  • Multi-track archives: several audio languages and subtitle tracks in one file.
  • Remuxing: repackage streams without re-encoding, fast and lossless.
  • Anything MP4 rejects: chapters, attachments, exotic codec combinations.

When is another format a better fit?

For playback on locked-down devices and browsers, MP4 is the safe container, since MKV plays everywhere with VLC but not on everything native. For the open web, WebM is literally a Matroska subset with web codecs only.

The short version: MKV is the universal media container: put anything in it, and convert to MP4 when the player is picky.

How to open a MKV file

On Windows

Double-click the file, or open it with MPC-HC.

On macOS

VLC opens MKV files on macOS.

In your browser

Open MKV files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • VLC
  • mpv
  • MPC-HC
  • MKVToolNix

View or convert MKV files

A quick preview or a new format. No install, no upload.

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MKV technical details

Full name
Matroska video
Extensions
.mkv
MIME type
video/x-matroska
Magic bytes
1A 45 DF A3 (EBML)
Compression
Lossless or lossy
Developer
Matroska.org / Steve Lhomme
Specification
www.matroska.org

MKV questions, answered

How do I open an .mkv file?

VLC, mpv, Plex and most players open it natively; browsers and consoles often do not. dexrr plays and converts mkv files directly in your browser.

Can I convert MKV files online?

Yes, dexrr converts mkv locally in your browser: MKV to MP4 for universal playback or MKV to WEBM for the web.

Is MKV better than MP4?

As a container, it is more capable: more tracks, chapters, attachments, any codec. As a delivery format, MP4 wins because everything plays it without thinking.

Why won't my TV/phone play .mkv?

Hardware players whitelist containers and codecs, and many simply never implemented Matroska. Remux or convert to MP4.

Is the MKV format outdated?

No, it is actively maintained, the basis of WebM, and still the enthusiast standard for multi-track video.