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Convert WEBM to MKV

Turn WEBM files into MKV in seconds — free, secure, and no signup required.

Free tier: 5 conversions/day, files up to 50 MB, ad-supported. Need more? See Pro plans →
  • 256-bit SSL encryptionYour files are protected end-to-end
  • Lightning-fast conversionsProcess files in seconds, not minutes
  • All major video formatsMP4, AVI, MOV, MKV & more
  • No registration requiredStart instantly — 5 free conversions a day
  • Files auto-deleted in 1 hourGDPR-friendly: we never keep your files
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Select or drop a file here

Max file size 50 MB. Sign up for more

Select several files to convert them in one go.

Rewrapping WebM as MKV is a pure container change — the two share the same underlying structure, so files convert losslessly in seconds. The point is flexibility: full Matroska lifts WebM's codec restrictions and adds room for subtitles, chapters, and extra tracks.

Convert WEBM to MKV – Free Online WEBM to MKV Converter

Why convert WEBM to MKV?

  • Add soft subtitles, chapter marks, or a second audio track to a recording that started life as WebM.
  • Standardize a mixed archive on MKV so every file supports the same metadata features.
  • Prepare downloaded VP9 or AV1 video for media libraries organized around Matroska files.

Tip: No quality question even arises — the VP9 or AV1 stream is copied bit-for-bit into the new container, and the operation runs as fast as the disk can read the file.

How to convert WEBM to MKV

  1. Upload your WEBM file using the area above.
  2. MKV is preselected as the target format.
  3. Click Start and wait for the conversion to finish.
  4. Download your converted MKV file.
Convert to MKV
MP4 to MKVAVI to MKVMOV to MKVFLV to MKVWMV to MKVMPEG to MKV
Convert from MKV
MKV to MP4MKV to AVIMKV to MOVMKV to FLVMKV to WMVMKV to MPEG
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WEBM to MKV — Frequently Asked Questions