Convert MKV to WEBM
Free online MKV to WEBM converter that runs in your browser. Your files stay on your device.
How to convert MKV to WEBM
- Add your MKV file. Drag it onto the box above, click to browse, or paste it from the clipboard. Multiple files are fine.
- Check the target. WEBM is preselected. Pick High, Medium or Small quality depending on whether you need a master copy or a small file.
- Download. The conversion engine loads once (32 MB) and then your file is processed locally. The WEBM file downloads automatically when it is done.
Why convert MKV to WEBM?
MKV files downloaded from the web often will not play or upload where you need them. WEBM is the format browsers play natively and the smallest for web embedding.
MKV vs WEBM
| MKV | WEBM | |
|---|---|---|
| Full name | Matroska Video | WebM |
| Type | Video | Video |
| MIME type | video/x-matroska | video/webm |
| About | MKV is a flexible open container that can hold multiple audio tracks, subtitles and chapters. Popular for downloads and archiving, but not supported by iPhones or many TVs. | WEBM is an open, royalty-free format from Google built for the web. Small files with VP8/VP9 video; native in Chrome, Firefox and Edge. |
What makes this converter different
- Nothing is uploaded. Other converters send your file to a server, queue it, and keep a copy for hours. Here the work happens in your browser with WebAssembly, so private videos, voice memos and documents never leave your computer.
- No limits, no sign-up, no watermark. There is no server to pay for, so there is no reason to cap file size or count.
- Real ffmpeg quality. Video and audio use the same ffmpeg encoders professionals use (x264, LAME, libvpx, FLAC), not a stripped-down web codec.
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Frequently asked questions
Is it safe to convert MKV to WEBM here?
Yes. The conversion runs entirely inside your browser using WebAssembly. Your file is never uploaded to a server, so nothing can leak, be stored or be seen by anyone. You can even disconnect from the internet after the page loads.
How long does MKV to WEBM conversion take?
Video encoding in the browser runs at roughly 0.5–2× real time depending on your CPU and resolution. A 1-minute 1080p clip takes about 1–2 minutes. Long or 4K videos can take a while; a desktop computer is much faster than a phone.
Is there a file size limit?
There is no server-side limit because there is no server. The practical limit is your device memory: browsers can handle files up to about 2 GB. Very large videos work better on a desktop than a phone.
Will the quality drop?
WEBM is a lossy format, so a small amount of detail is discarded. At the default Medium setting the difference is invisible or inaudible for almost all content. Choose High for master copies or Small for messaging and web use.
Can I convert several MKV files at once?
Yes. Drop or select as many files as you like; they are converted one after another and each gets its own download button.