Convert MKV to WebM Online
Free, private MKV to WebM converter. Your files never leave your browser. All processing happens locally on your device.
Drag & drop files here
images, PDFs, documents, audio, video, and more
No Server Uploads
FormatShift converts files directly in your browser. Your files never leave your device, so there's nothing to intercept or leak.
Instant Export
Files convert on your machine, so downloads are ready right away, even on slow connections.
High Fidelity
Good encoding keeps your files looking and sounding right, even at smaller sizes.
Built for Privacy
Your files are processed entirely in your browser. They never leave your device.
How to convert MKV to WebM
Drop your MKV file
Drag your file onto the converter above, or click to browse your files. Your files stay on your device.
Automatic conversion
FormatShift converts your file right in your browser using WebAssembly. No server involved, so your data stays completely private.
Download your WebM file
Once the conversion finishes, click the download button and you are done. The converted file is ready to use.
Why convert MKV to WebM?
MKV and WebM serve different purposes. Converting between them lets you use whichever format works best for your situation.
What is a MKV file?
Matroska Video: MKV is a flexible, open-source video container popular for high-definition movies and TV shows. It can hold multiple audio tracks, subtitles, and chapters in a single file, which is why movie rips often use it.
Created by: Matroska team, first released in 2002
Used for: HD movie files, TV show collections, videos with multiple audio/subtitle tracks
Technical details: Open container format supporting virtually any video and audio codec. Supports multiple audio tracks, subtitle streams, chapter markers, and metadata.
Compatibility: Supported by VLC, most desktop media players, and some smart TVs. Not natively supported by web browsers or many mobile players.
What is a WebM file?
WebM Video: WebM is Google's open video format designed for the web. It tends to produce smaller files than MP4 while keeping comparable quality, though compatibility outside of web browsers is more limited.
Created by: Google, first released in 2010
Used for: Web video, HTML5 video elements, web applications
Technical details: Container format using VP8/VP9 video and Vorbis/Opus audio. Open and royalty-free. Good compression efficiency.
Compatibility: Supported by all major browsers (Chrome, Firefox, Edge, Safari). Desktop media players like VLC handle it. Some mobile apps and editors may not.
MKV vs WebM
| Feature | MKV | WebM |
|---|---|---|
| Type | Matroska Video | WebM Video |
| Best for | HD movie files, TV show collections, videos with multiple audio/subtitle tracks | Web video, HTML5 video elements, web applications |
| Compatibility | Supported by VLC, most desktop media players, and some smart TVs. Not natively supported by web browsers or many mobile players. | Supported by all major browsers (Chrome, Firefox, Edge, Safari). Desktop media players like VLC handle it. Some mobile apps and editors may not. |
| Pros | Extremely flexible, supports multiple streams, open format | Smaller files than MP4, open and royalty-free, excellent browser support |
| Cons | Not supported by browsers, less compatible than MP4 for sharing | Less compatible than MP4 outside of browsers, limited editing tool support |