MKV to WebM converter
A free MKV to WebM converter for Matroska Video files. Browser-based pairs here usually run in this tab, with no file upload.
Drop your MKV files here
or browse your device · paste with Ctrl+V
Accepts .mkv files. You can queue several files; each is processed one after another on your own device.
Your files never leave this device — there is no upload and no server to delete them from.
- 01
Add your MKV files
Drop them onto the box above or click to browse. They are read straight from disk — nothing is sent anywhere.
- 02
Check the settings
WebM is already selected. Open the gear icon on any row if you want to change quality, dimensions or codec before converting.
- 03
Download your WebM
Press convert and wait for the row to finish. Convert several files and you can take them all as a single ZIP.
MKV
Matroska VideoAn open container with no practical limits: unlimited audio tracks, subtitle tracks, chapters and attachments in one file. Favoured for archived films because it preserves everything, though native browser support is thin.
- Developed by
- Matroska (CoreCodec)
- Released
- 2002
- Extension
- .mkv
- MIME type
- video/x-matroska
- Compression
- Lossy
- Specification
- Open
WebM
WebMGoogle's royalty-free container built for HTML5 video, pairing VP8 or VP9 with Vorbis or Opus. Smaller than H.264 MP4 at matching quality, and supported by every current browser.
- Developed by
- Released
- 2010
- Extension
- .webm
- MIME type
- video/webm
- Compression
- Lossy
- Specification
- Open
- Both MKV and WebM are lossy formats, so repeated conversions can accumulate rounding artifacts. Keep this to only what you need and avoid repeated round-trips.
Questions about converting MKV to WebM
Is this MKV to WebM converter free?
Yes. Converting MKV to WebM here is free, with no account, no watermark and no daily quota. The work runs on your own device, so there is no server cost to pass on to you.
Is my MKV file uploaded anywhere?
For browser-based pairs, your file is read locally and converted by ffmpeg in this tab. No file payload is uploaded; you may still see analytics and engine downloads in network logs.
Is there a file-size limit for MKV to WebM?
There is no imposed upload cap when it runs in-browser, but each conversion still depends on your device and browser memory. Large videos are the first practical limit, then memory-heavy documents or images.
Does converting MKV to WebM lose quality?
WebM is a lossy format, so some detail is discarded when it is encoded. At the default quality setting the change is often not visually obvious; keep your original MKV file if you might need it again.
Can I convert several MKV files to WebM at once?
Yes. Drop in several files and each gets its own row; they are processed one after another on your device. You can download them one by one or as one ZIP.
Does MKV to WebM work on a phone, Mac or Chromebook?
Most modern browsers on Windows, macOS, Linux, ChromeOS, Android and iOS work. Very large videos are often more reliable on desktop or a browser with more memory.
Why do some conversions take longer on first run?
The conversion engine has to download first. Small codec bundles are fast, while ffmpeg is commonly 12–30 MB; later conversions of similar type use the cached engine.
I converted a file and the output is blank or unusable. What should I check?
Start over with default settings, then change one option at a time (quality, bitrate, page size, or codec) to isolate what changed behavior. If it keeps failing, retry with a smaller file and confirm the source format matches the pair.
Convert other formats to WebM
21 formats can become WebM here.
Convert MKV to other formats
A MKV file can become any of these.
WebM to MKV
The reverse conversion
MKV to MP4
MKV to MP3
MKV to WAV
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