MKV to MP4 converter

OBS and many downloads save MKV, but phones, iMovie, Premiere uploads and most social sites want MP4.

Drop a MKV file hereThe converter loads in your browser.

What happens to your MKV

MKV with H.264/HEVC video and AAC/MP3/AC-3 audio is remuxed into MP4 without re-encoding. Vorbis, FLAC or DTS audio is converted to AAC; the video stays untouched where possible. Soft subtitles in MKV (ASS/SRT) are dropped because MP4 supports only a basic text subtitle format.

Tip: OBS users: remuxing MKV to MP4 is exactly what OBS's own "Remux Recordings" does, and it runs just as fast here.

How to convert MKV to MP4

  1. Drop your MKV file on the box above, or tap it to pick one. The engine (about 31 MB) loads once per visit.
  2. The converter reads the file's streams and shows which codecs are inside.
  3. Keep the defaults, or pick a quality and resolution.
  4. Press the button, wait for the progress bar, then download your MP4.

Questions

Will I lose subtitles?

Embedded MKV subtitle tracks are not carried over. Keep the MKV if you need them, or burn them in with desktop FFmpeg.

Why did it finish in seconds?

Because nothing was re-encoded. The video packets were copied into a new container.

Is my MKV file uploaded?

No. The MKV is read from your device by FFmpeg running as WebAssembly in the page, and the MP4 is written back to your device. No server ever receives it.

Is there a size limit for MKV to MP4?

We set none. The practical limit is browser memory: roughly 2 GB of output on a computer, and much less on phones.