MKV to MP3 Converter

MKV (Matroska) files often carry several soundtracks — the original language, a dub, a commentary — in formats such as AC-3, E-AC-3, DTS, FLAC, Opus or AAC, which many music players cannot read. This converter pulls out the track you choose and saves it as an MP3 that plays on any phone, car stereo or music app. Surround sound is mixed down to stereo. It runs in your browser with the ffmpeg engine (about 30 MB, downloaded once), so the film never leaves your computer.

How to use this tool

1. Choose one or more .mkv files.
2. Convert once with audio track 1: the notes list every track with its language and format.
3. Set the track number you want, the MP3 quality and mono or stereo.
4. Optionally enter a start and end time to keep one scene or song, then download the MP3.

Formula

MP3 size ≈ bitrate (kbps) × 125 × length (seconds) bytes

The chosen track is decoded to PCM and encoded with LAME, the reference MP3 encoder. 5.1 and 7.1 surround tracks are mixed down to stereo, because MP3 holds at most two channels; a centre-heavy dialogue track stays clear. The file name becomes the MP3's title tag.

Example

A 2-hour MKV film, converting its English AC-3 5.1 track at 192 kbps stereo: 192 × 125 × 7,200 = 172,800,000 bytes, about 165 MB. A 3-minute concert scene cut out with start and end times at the same bitrate is about 4.1 MB.