Convert MKV to WEBM
MKV is great for movies with multiple audio tracks and subtitles, but WEBM is the better choice for web video, HTML5 players and screen recordings. Convert MKV to WEBM in seconds, right in your browser.
- No upload — 100% private
- Fast, lossless when possible
- Free & unlimited
- Works on iPhone & Android
Keep this tab open — the conversion runs on your device, nothing is uploaded.
Add more files above to keep converting.
How to convert MKV to WEBM
- 1
Tap Choose files and select one or more MKV files (or drag them in).
- 2
Check that WEBM is selected. Use Advanced options for resolution, size or trimming.
- 3
Press Convert. Everything happens on your device — no upload, no waiting in a queue.
- 4
Your WEBM downloads automatically. Converting several files? Grab them all as a ZIP.
MKV vs WEBM
Both formats are lossy, so the video is re-encoded once. Pick High quality to keep it as close to the original as possible, or Small for the smallest file.
| MKV | WEBM | |
|---|---|---|
| Full name | Matroska Video | WebM Video |
| Type | Video | Video |
| Compression | Lossy | Lossy |
| Developed by | Matroska.org | |
| Introduced | 2002 | 2010 |
| Plays on iPhone | ✕ No | ◐ Partly / with an app |
| Plays on Android | ◐ Partly / with an app | ✓ Yes |
| Plays on Windows | ✓ Yes | ✓ Yes |
| Plays on Mac | ◐ Partly / with an app | ◐ Partly / with an app |
About MKV and WEBM
MKV: MKV is a flexible open container that can hold unlimited video, audio and subtitle tracks. It is popular for movies and anime but isn't supported by iPhone or most TVs out of the box.
WEBM: WebM is Google's open video format using VP8/VP9 and Opus. It is built for the web and is what screen recorders and browsers produce.
Frequently asked questions
How do I convert MKV to WEBM on my phone?
Will converting MKV to WEBM reduce quality?
Is this MKV to WEBM converter free?
Are my files uploaded to a server?
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