01
ADD YOUR WEBM
Drop the WEBM file into the box above or choose it from your device.
WEBM → MKV / online converter
WEBM to MKV Converter
Convert a WebM video to MKV for media servers and players like Plex, Jellyfin and VLC.
01 / how to
How to convert WEBM to MKV
02
CONVERT TO MKV
MKV is already selected. Press Convert and wait a few seconds.
03
DOWNLOAD
Save the finished MKV file. The original is deleted from our server.
02 / what you get
What happens to your data
Kept
- VP8 and VP9 video with Opus or Vorbis audio is read
- H.264 video with AAC audio in a Matroska container that plays in VLC, Plex, Jellyfin and most media players
- The original resolution and frame rate are kept
- A phone video recorded sideways or upside down is turned the right way up
- Surround sound (5.1) is kept when the source has it
Good to know
- The video is re-encoded, which is slightly lossy. Only one video track and one audio track are kept; extra audio tracks and subtitles are left out.
- A width or height that is an odd number of pixels is trimmed by one pixel, because video encoders need even sizes.
- HDR video (for example from a recent iPhone) is converted to normal SDR colors, and 10-bit video becomes 8-bit, so it plays everywhere.
- Files up to 150 MB are accepted. Long or very high-resolution videos can take several minutes, and a conversion that runs past about 4 minutes is stopped with a message.
03 / formats
WEBM vs MKV
WEBM
A WebM file is an open, royalty-free video format built for the web — what YouTube and most browsers use natively for efficient streaming and playback.
Used in: YouTube & web streaming · Browsers · Open-source apps
MKV
An MKV (Matroska) file is an open-standard, highly flexible video container — popular for media archiving, torrents, and playback through apps like Plex or Jellyfin.
Used in: Media archiving · Plex & Jellyfin · Torrents
04 / more
More conversions
Have a different file? Open the main converter — it detects the format for you.