How to convert MKV to WEBM
To convert MKV to WEBM, upload your MKV file, choose WEBM as the output format and press Convert. The finished WEBM file is ready to save to your phone or computer in seconds, free, with no watermark and no sign-up. Your file is deleted from our server about 30 minutes after the conversion.
This free online converter turns MKV videos into WEBM files in your browser, with no software to install and no watermark. When the video and audio inside your MKV file can be placed in WEBM as they are, the streams are copied without re-encoding, which is faster and keeps the original quality. Otherwise the video is re-encoded as VP9 video with Opus audio.
Why convert MKV to WEBM?
- Designed for the web and royalty-free
- Plays natively in Chrome, Firefox, Edge and Android
- Efficient VP9 compression
- Plays on: Chrome, Firefox, Edge, Opera, Android and VLC; partial on Safari and iOS
What to expect from this conversion
- Expect a file of similar size to the MKV original.
- WebM uses VP9, which compresses very well but takes longer to encode than H.264, so large videos need patience.
- The first audio track is kept. Subtitle tracks, extra audio tracks and chapters are not included in the converted file.
MKV vs WEBM
| Property | MKV | WEBM |
|---|---|---|
| Full name | Matroska Video | WebM |
| Released | 2002, Matroska.org (open standard) | 2010, Google |
| Generation | Modern | Modern |
| Typical file size | Small | Small |
| Plays on | VLC, Plex, Kodi, most Android players and modern Windows; limited on iOS and older TVs | Chrome, Firefox, Edge, Opera, Android and VLC; partial on Safari and iOS |
| Best for | movie and TV archives with multiple languages; keeping subtitles inside the file | embedding video on your own website; short looping clips and web animations |
Steps to convert MKV to WEBM
- Drop your MKV video file onto the converter, or click to choose it.
- Check that WEBM is selected as the target and adjust the options if you want.
- Press Convert, then download your new WEBM file when it finishes.
Tips for the best result
- Leave Fast mode on to keep the original quality whenever the streams can be copied.
- Pick a lower resolution if the file is for a phone or messaging app.
- Use Mute if you only need the picture.
Frequently asked questions
How do I convert MKV to WEBM?
Upload your MKV file, make sure WEBM is the selected target and press Convert. When the progress bar finishes, download the WEBM file. No account or software is needed.
Is the MKV to WEBM converter free?
Yes. It is free, with no watermark, no sign-up and no daily limit on how many files you convert. The site is supported by ads.
Will I lose quality when converting MKV to WEBM?
Not necessarily. If the video and audio streams already fit inside WEBM, they are copied without re-encoding, so quality stays identical. If the file has to be re-encoded, the High setting keeps almost all visible detail, while Small trades some detail for a smaller file.
Will the WEBM file be a similar size to my MKV?
Expect a file of similar size to the MKV original. Choosing a lower quality or resolution reduces the size further.
Which devices can play WEBM files?
WEBM files play on Chrome, Firefox, Edge, Opera, Android and VLC; partial on Safari and iOS.
How large a file can I upload?
You can upload videos up to 500 MB. Files are deleted from the server about 30 minutes after conversion.