WebM to MKV Converter
Convert WEBM to MKV online for free. WebM to MKV in seconds — no software install, no watermark, secure and fast.
Drag & drop your WEBM file here, or
How to convert WebM to MKV in 3 steps
- 1
Upload your WebM file
Drag and drop or select the WebM file you want to convert.
- 2
Choose MKV as output
The output format is pre-selected for you — just confirm and start the conversion.
- 3
Download your file
Once processing finishes, download your converted MKV file instantly.
Benefits of converting WebM to MKV
Get support for multiple audio/subtitle tracks and near-lossless quality
Switching from WebM to MKV means your file now offers support for multiple audio/subtitle tracks and near-lossless quality, ideal for archiving.
Wider compatibility
WebM is great for royalty-free, but not every app or device handles it well. Converting to MKV sidesteps that, so the file opens wherever you need it to.
No quality compromise
ConvertFastHub runs FFmpeg at production settings, preserving as much of the original WebM fidelity as the MKV format allows.
Keep your original too
Converting doesn't touch your source file — you get a brand-new MKV file back and can keep both versions.
Frequently asked questions
- How do I convert WebM to MKV online?
- Upload your WebM file above, select MKV as the output format, and click Convert. ConvertFastHub processes the file in the cloud and gives you a download link — no software installation required.
- Is it free to convert WebM to MKV?
- Yes. Free accounts get 10 conversions every 24 hours with files up to 50MB. For unlimited conversions, larger files up to 1.5GB, and priority processing, upgrade to ConvertFastHub Pro.
- What's the advantage of MKV over WebM?
- MKV offers support for multiple audio/subtitle tracks and near-lossless quality, ideal for archiving. Meanwhile, WebM is known for royalty-free, highly optimized playback for the web — the right choice depends on where you plan to use the file.
- Will converting WebM to MKV reduce quality?
- ConvertFastHub uses production-grade engines (FFmpeg, LibreOffice, ImageMagick) configured for maximum fidelity. Some format conversions are inherently lossy by design; where possible, we preserve the original quality.
- Is my file safe when I convert it?
- Files are uploaded over an encrypted connection directly to storage, processed in an isolated sandboxed worker, and permanently deleted within 24 hours.