Video · 1 min read
What is MKV?
MKV is common in movies and archives but does not always open on a phone or TV. Here is what the format is and how to get a compatible MP4.
Updated: November 2, 2026
What is MKV
MKV (Matroska Video) is a container, not a codec. It can store video, multiple audio tracks, subtitles and chapters in one file. That flexibility makes MKV popular for movies and archives.
Why MKV does not always open
Support depends not on the extension but on the codecs inside and the player. iPhone, many TVs and social networks do not open MKV or some tracks. They need MP4 with H.264/AAC.
How to convert MKV
- To MP4 — for iPhone, Android, TVs and social media.
- To WebM — for websites and modern browsers.
- To MOV — for QuickTime and Final Cut.
Our converter processes MKV on the server, re-encodes video to H.264/AAC and deletes files automatically. Keep the original for an archive with multiple tracks.
Limitations
The current version transfers the main video track and the main audio. Subtitles and additional audio tracks are not preserved. The maximum size is 100 MB, duration is 5 minutes and resolution is Full HD.
Questions and answers
Is MKV a codec or a container?
It is the Matroska container. It can hold different video and audio codecs, as well as subtitles and multiple audio tracks.
Why does MKV not open on iPhone?
iPhone and many mobile players do not support the MKV container and some codecs. MP4 with H.264/AAC opens without extra apps.
Are subtitles preserved during conversion?
The current version keeps the main video track and the main audio. Subtitles and additional tracks are not preserved.
MKV or MP4 for archiving?
MKV is convenient for archives with multiple tracks and subtitles. MP4 is better for playback on devices and publishing.