What happens when you convert WebM to MKV
| Inside a typical WebM | VP8, VP9 or AV1 video with Opus or Vorbis audio |
|---|---|
| Copy without re-encoding | Yes, almost always: MKV accepts any codec, so streams are copied in seconds |
| When re-encoded | H.264 video with AAC audio |
| Extra tracks | Your file's first video and audio track are kept |
| Opens in | VLC, mpv, Plex and most smart TVs; browsers, iPhones and editors often do not |
Sizes are typical values; your files will vary with content and settings.
WebM WebM Video
WebM is an open, royalty-free container built for the web, usually holding VP8 or VP9 video with Opus or Vorbis audio. Browser screen recorders and many web apps save WebM by default.
WebM converterMKV Matroska Video
MKV is an open container that can hold almost any codec plus multiple audio tracks and subtitles. It is popular for archived films and series.
MKV converterHow to use the WebM to MKV Converter
- 1
Choose a WebM file or drop it onto the page.
- 2
Review the video options. The defaults suit most files.
- 3
Click Convert and download your MKV when processing finishes.
Why convert WebM to MKV?
WebM files come from videos saved from websites and from browser-based screen recorders. iPhones, some TVs and many editors play it poorly or not at all. Choose MKV to repackage video without re-encoding, since it accepts any codec.
Frequently asked questions
Will the MKV lose quality?
Both formats are lossy, so converting re-encodes the data once more. Using a high quality setting keeps the generational loss very small. Avoid converting the same file back and forth repeatedly.
Does converting WebM to MKV re-encode the video?
Yes, almost always: MKV accepts any codec, so streams are copied in seconds. A typical WebM contains VP8, VP9 or AV1 video with Opus or Vorbis audio. Otherwise the result is H.264 with AAC audio.
Questions about privacy, file-size limits or conversion speed are answered in the general FAQ.