Convert WebM to MKV
Turn your WebM file into an MKV that plays where you need it, right in your browser.
- Free to start
- In your browser
- Up to 500 MB
How to convert WebM to MKV
Upload your WebM file
Drag and drop a WebM file, or click to browse. Up to 500 MB, and nothing is installed.
Confirm MKV as the output
MKV is already selected, so there is nothing to configure. Switch to another format in the panel if WebM needs to go somewhere else.
Convert and download
We convert the WebM on our servers, usually in under a minute. Create a free account to download the MKV, or keep editing it in REQO.
Why convert WebM to MKV?
WebM is the open, royalty-free container built for the web. It is what most browser-based screen recorders produce, and VP9 packs the same picture into noticeably less data than H.264.
The practical problem: Most editing software, phones and TVs will not open a WebM file. Social platforms and messaging apps frequently reject the extension outright. Safari and older Apple devices handle WebM inconsistently.
MKV solves that. Keeps multiple audio and subtitle tracks in one file.
Container
Typical codecs
Best for
Plays on
File size
| Feature | WebM | MKV |
|---|---|---|
| Container | WebM (Matroska-based) | Matroska |
| Typical codecs | VP8 / VP9 / AV1 video, Opus audio | Almost anything: H.264, HEVC, AV1, VP9 |
| Best for | Web embeds and browser recordings | Archiving with multiple audio and subtitle tracks |
| Plays on | Chrome, Firefox and Edge; hit and miss elsewhere | VLC and desktop players; rarely anywhere else |
| File size | Very small at the same quality | Depends entirely on the codec inside |
WebM to MKV questions
Is the WebM to MKV converter free?
Yes. Convert and preview the result for free, then create a free account to download it. There is no per-file charge and no watermark on the MKV itself beyond the free-plan badge.
Do I need to install any software?
No. The conversion runs on our servers and the whole flow happens in your browser, so it works the same on Windows, macOS, Linux, iPhone and Android. Nothing to install at either end. Where WebM plays: Chrome, Firefox and Edge; hit and miss elsewhere. Where the MKV you get back plays: VLC and desktop players; rarely anywhere else.
Does converting WebM to MKV reduce the quality?
Converting re-encodes the video, so it is not bit-for-bit identical. We encode at a high quality target, which keeps the result visually indistinguishable from the WebM on normal viewing. What changes is the container and the codec. MKV holds: Almost anything: H.264, HEVC, AV1, VP9. Converting the same file back and forth repeatedly will eventually show, so keep your original.
How large a file can I convert?
Up to 500 MB per file, which is more footage in some formats than others. WebM: Very small at the same quality. MKV coming back: Depends entirely on the codec inside. For anything bigger, trim or compress it first, both are free tools here.
Is my file kept private?
Your upload is processed and then held only as long as your project needs it. Nothing is published, indexed or shared unless you create a share link yourself.
Other formats
Everything else you can do here.
Convert to MP4
Convert to WebM
Convert to MOV
Convert to AVI
Convert to MKV
Convert to WMV
Convert to MP3
Convert to M4A
Convert to AAC
Convert WebM to MKV now
Free, in your browser, and the file stays open in a full video editor afterwards.