Convert WebM to MKV Online
WebM is an open, royalty-free multimedia container developed for the web. MKV is a flexible, open container format capable of holding virtually any video or audio codec, multiple subtitle tracks, chapters, and attachments. AnyConvert converts WebM to MKV securely without installing desktop software.
WebM to MKV Converter
Convert your WEBM files to MKV format quickly and easily. Upload your file and download the result.
Max file size: 50MB
Why convert WebM to MKV?
Switching from WebM helps you avoid native support on ios safari arrived only recently (14+), limiting legacy compatibility. MKV excels at supports multiple video, audio, and subtitle streams with rich metadata, making it a better fit when clients or platforms expect home media libraries managed with plex or jellyfin.
Matroska Multimedia Container also offers ideal for preserving blu-ray and uhd rips with high bitrate codecs. That means your converted files stay useful for home media libraries managed with plex or jellyfin and preserving disc extras, commentary tracks, and subtitle variants.
WebM strengths
- Royalty-free alternative to MP4 with excellent compression efficiency
- Seamless HTML5 video integration and adaptive streaming support
- Supports alpha transparency with VP8/VP9, enabling overlay animations
MKV advantages
- Supports multiple video, audio, and subtitle streams with rich metadata
- Ideal for preserving Blu-ray and UHD rips with high bitrate codecs
- Extensible design accommodates modern codecs like AV1 and Opus
Key differences
| Feature | WebM | MKV |
|---|---|---|
| Compression | Lossy | Lossy or lossless |
| Transparency / Alpha | Not applicable | Not applicable |
| Typical file size | Compact (lossy compression) | Varies (depends on chosen codec) |
| Best suited for | Web-native video delivery through HTML5 players and Animated backgrounds and UI components requiring transparency | Home media libraries managed with Plex or Jellyfin and Preserving disc extras, commentary tracks, and subtitle variants |
| Standard | Open, royalty-free specification | Open, royalty-free specification |
Before you convert
- Keep a backup of your original file before converting so you can roll back if needed.
- Review known pain points: Hardware acceleration varies, impacting playback on older devices. Adjust your source file accordingly.
- Note the target resolution and frame rate to avoid unexpected stretching or stutter.
Quality tips
- Trim clips and set the frame rate before converting to avoid double-encoding footage you do not need.
- Download the result immediately and open it in the target application to verify everything matches expectations.
Where MKV fits best
Once you have the converted file, you can plug it straight into home media libraries managed with plex or jellyfin, preserving disc extras, commentary tracks, and subtitle variants, and encoding high-quality screencasts or screen recordings for archival. MKV is the format teams expect in those environments, so you spend less time re-exporting or explaining compatibility issues.
Common MKV use cases
- Home media libraries managed with Plex or Jellyfin
- Preserving disc extras, commentary tracks, and subtitle variants
- Encoding high-quality screencasts or screen recordings for archival
Tools that open MKV
- MKVToolNix
- HandBrake
- FFmpeg
Frequently asked questions
Does converting WebM to MKV reduce quality?
No—MKV preserves the original fidelity. You still want to open the converted file once to confirm fonts, colors, or audio loudness survived the transfer.
How can I keep MKV file sizes reasonable?
Trim the clip, export with a constant or target variable bitrate, and align the frame rate with your footage. Dropping unused audio tracks also saves space.
Is there a file size limit for converting WebM?
Yes—uploads up to 150 MB convert reliably in the browser. For larger assets, split them into smaller segments first so the process stays responsive.