What Is an MKV File?

How to Open, Edit, and Convert MKV Files

Screenshot of several MKV files in Windows 10
MKV Files.

file with the .MKV file extension is a Matroska Video file. It's a video container much like MOV and AVI, but also supports an unlimited number of audio, picture, and subtitle tracks (like SRT or USF).

This format is often seen as the carrier for high-def online video because it supports descriptions, ratings, cover art, and even chapter points. It's for these reasons that it was chosen as the default video container format for the popular DivX Plus software.

How to Play MKV Files

Opening MKV files might sound like an easy task but if you have a collection of 10 videos you got from 10 different places, you might find that you can't play all of them on your computer. This is because the correct codecs are necessary to play the video. There's more information on that below.

That said, your best bet for playing most MKV files is to use VLC. If you're on Windows, some other MKV players include MPV, MPC-HC, KMPlayer, DivX Player, MKV File Player, or The Core Media Player (TCMP).

Some of those applications can be used to open an MKV file on macOS, too, as can Elmedia Player. Though not free, Roxio software can be used to play MKV files on macOS as well.

On Linux, MKV files can be played using xine and some of the programs above that work with Windows and Mac, like VLC.

Playing MKV files on iPhones, iPads, and iPod touches is possible with the free PlayerXtreme Media Player or VLC for Mobile apps. VLC works with Android devices as well, as does Simple MP4 Video Player (it's named as such because MP4s and other video formats are supported).

You can use the CorePlayer mobile software to open MKV files on Palm, Symbian, Windows Mobile, and BlackBerry devices. However, the software is not free.

Note: The Matroska.org website has a list of decoder filters that must be installed for certain MKV files to play on your computer (in the Additional playback Information section). For example, if the video is compressed with DivX Video, you have to have either the DivX codec or FFDshow.

Since you might need different programs to open different MKV files, see How to Change the Default Program for a Specific File Extension in Windows. This is necessary if, say, KMPlayer is trying to open an MKV file that you instead want or need to use with DivX Player.

How to Convert an MKV File

A free video file converter is the easiest way to convert an MKV file to a different video format. Since videos files usually pretty large, an online MKV converter like Convert.Files probably shouldn't be your first choice.

Instead, it's recommended to use a program from that list, like Freemake Video Converter. You can use it to convert the MKV to MP4, AVI, MOV, or even straight to a DVD so you can burn the MKV file with little effort or knowledge of movie burning.

Tip: Freemake Video Converter is also useful if you want to rip/copy a DVD to the MKV format.

How to Edit MKV Files

You can add new subtitles to an MKV video or even remove them, plus make custom chapters for the video. The easiest way to do this is with the free MKVToolNix program for Windows, Linux, and macOS.

The supported subtitle formats include SRT, PGS/SUP, VobSub, SSA, and others. You can delete subtitles that are soft-coded into the MKV file or even add your own custom subtitles. The Chapter Editor portion of the program lets you make start and end times for custom video chapters.

Tip: If you're not using the GUI version of MKVToolNix, this command can remove the subtitles:

mkvmerge --no-subtitles input.mkv -o output.mkv

For other tips or help using MKVToolNix, see the online documentation.

To edit the length of an MKV file, cut out portions of the video, or merge multiple MKV videos together, you can use the Freemake Video Converter program mentioned above.

More Information on the MKV Format

Because the MKV file format is just a general container format, it can hold several different tracks that each use different compression formats. This means it's not so easy to just have a single MKV player that can open every single MKV file you have.

Certain decoders are necessary for certain encoding schemes, which is why some MKV files may work on one computer but not another - the program that reads the MKV file has to have appropriate decoders available. There's a really helpful list of decoders on the Matroska.org website.

If what you have is just an audio file that's related to the Matroska format, it might instead use the MKA file extension. MK3D (Matroska 3D Video) files are used for stereoscopic video and MKS (Matroska Elementary Stream) files just hold subtitles.

The Matroska project is supported by a non-profit organization and is a fork of the Multimedia Container Format (MCF). It was first announced to the public at the end of 2002 and is a completely royalty-free open standard that's free for both private and commercial use. In 2010, Microsoft confirmed that Windows 10 would support the Matroska format.