MKV to WEBM Converter

Convert MKV files to WEBM free in your browser — no signup, no install, and the file is never uploaded to a server. WEBM compresses further, so the file gets noticeably smaller.

Completely free Files are never uploaded No signup required
Drop files or click to select
MKV → WEBM

What changes in this conversion

  • WEBM uses lossy compression, so some picture detail is discarded permanently in exchange for a much smaller file.
  • WEBM is a newer format — check that the software or device you are sending it to supports it before switching.
  • Both MKV and WEBM are lossy, so re-encoding discards a little more picture detail on top of what was already lost. Converting once is fine; repeating it many times is not.
  • The picture and sound are re-encoded to H.264 video with AAC audio inside the WEBM container, which is what makes the result play on the widest range of devices.

How to use

  1. Add your MKV file

    Drag the MKV file onto the drop area above, or click it to pick a file from your device. You can add several files at once.

  2. Confirm WEBM as the output

    WEBM is already selected as the output format on this page. You can pick the resolution. Encoding is the slowest part, so smaller resolutions finish sooner.

  3. Run the conversion

    Press the convert button. Video is re-encoded frame by frame on your own machine, so a long clip can take several minutes. The tab has to stay open.

  4. Download the WEBM file

    When it finishes, download the WEBM file. Converting multiple files gives you the option to download them together as a ZIP.

About these formats

MKV Matroska Video

An open-source video container able to hold unlimited subtitles, audio tracks, and chapters. It is favored for archiving high-quality video.

Commonly used for High-quality video archives, multilingual subtitled video

MKV File format reference

WEBM WebM Video

An open video format created by Google for web streaming. It is royalty-free and compact, making it well suited to website background video.

Commonly used for Website video, browser streaming

WEBM File format reference

Frequently asked questions

Is converting MKV to WEBM really free?

Yes. MKV to WEBM conversion is completely free with no signup, no watermark, and no daily limit on the free plan for ordinary use.

Are my MKV files uploaded to a server?

No. The conversion runs entirely inside your browser using WebAssembly, so the MKV file never leaves your device. That is also why it works without an internet connection once the page has loaded.

Does converting MKV to WEBM reduce quality?

WEBM uses lossy compression, so some detail is discarded. At high quality settings the difference is usually invisible, and the file becomes far smaller.

Will the WEBM file open everywhere?

WEBM is a newer format. Current browsers and phones handle it, but older desktop software may not — keep the original MKV if you have to send it to someone on an old machine.

Is there a file size limit for MKV to WEBM conversion?

The free plan handles files up to 200MB. Because processing happens on your own device, very large files depend on your computer's memory rather than a server quota.

Convert MKV files to other formats

MKV AAC MKV AVI MKV FLAC MKV GIF MKV M4A MKV MOV MKV MP3 MKV MP4 MKV OGG MKV OPUS MKV WAV

Convert other formats to WEBM

3G2 WEBM 3GP WEBM ASF WEBM AVI WEBM DIVX WEBM F4V WEBM FLV WEBM M2TS WEBM M4V WEBM MOV WEBM MP4 WEBM MPE WEBM

Video converter

What each file format is, what it is used for, and which formats it can be converted to.

Open converter Browse the full format reference