Convert WebM to Matroska
We turn WebM into Matroska right in your browser — the file never goes to a server.
What you will lose
Nothing to lose, and nothing to gain: {to} keeps exactly what {from} hands over, and the file grows several times over.
How they differ
| WebM | Matroska | |
|---|---|---|
| Lossless | no | yes |
| Lossy | yes | yes |
| Multichannel | yes | yes |
| Tags | yes | yes |
| Released | 2010 | 2002 |
| Author | CoreCodec |
WebM
Good at
- The browser’s own format: plays with no plugins at all
- Free of patent fees, which is why sites reach for it
- Noticeably lighter than older-style MP4 at the same quality
Awkward about
- Household devices and editing software barely know it
- On Apple hardware it plays only sometimes
- Audio is lossy only: Vorbis or Opus
Use it when
- The video goes on a web page and is watched in a browser
- You want the smallest file with the picture still alive
- A screen recording or a short clip for a page
Matroska
Good at
- Takes anything inside: any codec, a dozen tracks, subtitle fonts
- The one common container people fill with lossless audio
- Tracks and subtitles can be swapped without touching the picture
Awkward about
- TVs and phones often refuse to open it
- No browser plays it directly
- Files run larger: what goes inside is usually less compressed
Use it when
- A home archive where everything should be kept as it was
- Several audio languages and subtitle tracks in one file
- The file is watched on a computer, not on household hardware
Common questions
- Does the file get uploaded to a server?
- Yes, this pair needs the server: browsers cannot encode that format. The file and the result are deleted within a couple of hours and never shared.
- Will surround sound survive?
- Yes, Matroska carries more than two channels — 5.1 stays 5.1.
- Can I get the original quality back afterwards?
- Nothing is lost, but nothing is gained either. Matroska stores exactly what WebM hands over, including the gaps WebM left behind when it compressed. No tool can bring those back, and the file grows several times over. This conversion makes sense for editing, not for quality.
- How many files, and how large?
- Up to 3 files at a time, 500 MB each. No sign-up, no watermarks.