webm to mkv

Convert your videos online from webm to mkv for free. You can select multiple formats to convert your videos.



or drag & drop here. The files supported are avi, flv, gif, mp4, mkv, mov, mpeg, swf, ts, vob, webm, wmv


WebM is an audiovisual media file format. WebM is perfect for HTML5 video and the HTML5 audio elements. The video container was Initially developed by On2, Xiph, and Matroska. Later on Google picked up the project and actively maintains the WebM container format. The inital release for this container was May 18, 2010. From the webmproject.com site, this is how webm is described (WebM is an open, royalty-free, media file format designed for the web.). The WebM file structure is based on the Matroska container.


MKV stands for Matroska Multimedia Container. It is a video container similar to MOVs and AVIs. The main difference is that an MKV format can hold unlimited amounts of audio, picture, and subtitle tracks (srt as an example). The MKV video format has the ability to store lots of useful information inside the container, like descriptions, ratings, cover art, and chapters. This is why MKV is the chosen format for DivX Plus software and DVDs since it was easy to display cover art and chapter information. MKV was initially released December 6 2002.

How you can convert webm to mkv

  1. 1. Upload Your webm file

    Simply drag and drop your webm file within the upload zone above. Alternatively you can click the big blue button that says "Upload File". If your file is not of webm type, then the system will automatically detect the file for you.

  2. 2. Select mkv as your conversion format

    Once your webm video is uploaded (it doesn't have to be webm, we will automatically detect the format if it's different), you will see a progress bar.

    In a matter of seconds (typically) you will see the video, with it's metadata on the right. At the top of the metadata you will see a format dropdown button. The default will be mkv, but you can change the format on the fly, once you're happy, you can click the convert button.

  3. 2. Download your mkv file

    Give it a few minutes to convert your webm file into mkv (or which ever formats you have defined). Depending on your settings and the output format it could take a moment.

    Be patient on this step, you can enter your email if you would like to get a downloadable link when it is ready. This is nice if you need to leave and get a link while on the go. When it's done you will have a free mkv file that you can download with no strings attached. If you would like to edit the video, then Motionbox has an awesome video editor for you.

Motionbox video converter illustration on how to use our webm to mkv converter
Motionbox video converter illustration on why you should use our webm to mkv converter

Why should you convert webm to mkv

  1. 1. Compatibility

    Depending on your purposes a webm file may need to be converted to a mkv file for compatibility purposes.

    Your file might not be supported by the device you are trying to add the file to. The Motionbox video converter tool is the perfect solution to make your files compatible with what ever device you are trying to upload your video on.

  2. 2. Social Media

    The pefect example is social media, typically the best format is MP4 (with H.264 or H.265 codecs) for sites like Instagram, Tik Tok, Twitter, YouTube, etc. So if you are converting your webm file for social media, we recommend MP4but you are free to convert it to mkv if you know what you are doing.

  3. 2. Easier Video Editing

    We highly encourage you to try our amazing video editing tool -- it's free. Since Motionbox is browser based we have found some issues with uploading MOV videos, so one thing you can try if you have issues with MOV is to convert it using our free converter.

    Then afterwards you can click "edit video" after the conversion process to import the video directly into our tool.

    This is not exclusive to MOV files, you can take webm files and convert them to mkv or any other imaginable video formats out there. Generally your best bet will be MP4 for our editor, and for other tools/apps.

Frequently Asked Questions

  • How can I convert webm to mkv quickly?
    It's as simple as uploading your webm file, or letting us automatically detect your file. Then you can press convert, choose mkv which is the default for this page, or you can change it to one of the other supported formats. Lastly press convert and wait a moment.
  • Is it free to convert webm to mkv?
    It is 100% free to convert your webm file, or which ever video file you would like to convert. All that we ask is you try out the Motionbox video editor after you convert and to spread the word if you like it.
  • Why use Motionbox to convert my webm files?
    Typically we run into issues ourselves where certain files are not the correct format for the software we want to use and need to convert them to a much more suitable format. Motionbox is the perfect video converter to help you re encode your webm file into a new container type that is more suitable for your needs. Typically MP4 is your best output format if you are trying to use within Motionbox or on Social Media sites like Instagram or Twitter.
  • Is it possible to edit my webm file with Motionbox?
    Personally I would recommend you use MP4 videos within Motionbox as some formats are not supported by Chrome or other major browsers.
  • Is it legal to convert webm to mkv
    Converting webm to mkv in itself is not illegal. However if the webm file contains material that has copyrights, and you are redistributing it without consent it can be illegal and is up to you to be responsible for handling the rights on the media you decide to upload.
  • Will I be able to compress my webm file
    We have settings in the converter step that allows you to tweak some settings which will enable you to compress your webm file as it gets encoded into a mkv file. These are technically advanced settings, but the compression should be straight forward.

Creating videos with Motionbox has been a delightful experience.

You can do so much more with Motionbox beyond converting webm to mkv. Motionbox is the ultimate online video editor that enables teams to collaborate on video editing, from the design team, to the copywriters, and CMOs. We make it easy for your team to add subtitles, adjust videos, slice videos, add keyframe animations, and so much more.

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