Free · No upload · No sign-up
Convert MP4 to MKV
Put your MP4 into a Matroska (MKV) container for multi-track audio, subtitle support, and media-library-friendly metadata — in your browser.
MP4MKV
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Drop your .mp4 file here
Converted to MKV in your browser.
Why this tool
Media-library friendly
MKV is the preferred container for Plex, Jellyfin, Kodi, and VLC — better support for chapters, subtitles, and multi-audio than MP4.
Private by default
Conversion runs in your browser. The MP4 never leaves your device.
Multiple tracks
MKV can hold many audio and subtitle streams side-by-side. Future updates will let you attach extra tracks here.
How to convert MP4 to MKV
- 1Drop your .mp4 file above.
- 2Pick a quality preset (Balanced keeps file size in check).
- 3Click Convert. Most streams are re-encoded to H.264 + AAC for compatibility.
- 4Download the .mkv — ready for Plex, Jellyfin, Kodi, or VLC.
Frequently asked questions
- Why use MKV instead of MP4?
- MKV is more flexible: it handles arbitrary codec combinations, multiple audio / subtitle tracks, chapter markers, and attachments. Media server software like Plex and Jellyfin generally recommends MKV.
- Is MKV playable everywhere?
- On desktop (VLC, MPV, mpc-hc) yes. On iOS it needs a player like VLC or Infuse. Many smart TVs play MKV natively.
- Does it re-encode my video?
- The MVP re-encodes to H.264 + AAC for safety. True stream-copy (rewrap only) is planned for a future update and will be near-instant.
- Does Clapr upload my file?
- No. Conversion runs in your browser via ffmpeg.wasm.
- Can I attach subtitles in the MKV?
- Not yet in this tool. Use our Burn Subtitles tool if you need captions baked in today; multi-track attachment is on the roadmap.