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Save the soundtrack of an MKV video as an MP3. Large files work because the video is read in pieces, and it never leaves your device.
Your media is processed in your browser and is not uploaded to our servers for conversion. Page assets (including the converter engine) still load over the network.
Select or drop a video or audio file
MP4, MOV, WebM, MKV, M4A, WAV, FLAC, OGG and more. Converted on your device.
Click, tap, or drop a fileChoose the MKV
Drop or select the .mkv file from your computer.
Pick the bitrate
192 kbps is preselected; use 128 kbps for talks and game commentary.
Convert
Only the first audio track is encoded, so it's fast even for long recordings.
Download the MP3
Check it, then download.
MKV (Matroska) is the default recording format in OBS Studio because a crash can't corrupt it, and it is common for films, anime and screen captures. People convert MKV to MP3 to keep a stream's commentary, a podcast recorded on video, a concert or a film soundtrack.
MKV files can hold several audio tracks, such as two languages or a separate microphone track from OBS. This tool converts the first audio track; if you need another one, remux the file with a desktop tool first.
FFmpeg in WebAssembly reads the MKV's first audio track, whether AAC, Opus, Vorbis, FLAC, MP3 or AC-3, and encodes it as MP3. The video is ignored, so it doesn't matter whether it's H.264, HEVC or AV1.
Surround (5.1) audio is mixed down to stereo, which is what MP3 supports.
Pull the audio out of streams and captures without re-rendering video.
AAC, Opus, Vorbis, FLAC, MP3 and AC-3 tracks.
Up to 4 GB and 4 hours on a computer.
Nothing is uploaded.
No. The conversion runs in your browser with a WebAssembly build of FFmpeg. Your file is read from your device and the result is saved back to it; nothing is sent to our servers.
The first audio track in the file. Selecting a different track isn't supported yet.
Yes. Surround tracks are mixed down to stereo MP3.
Yes. MKV to MP4 remuxes or converts the video so it plays on phones and in editors.
Files up to 4 GB and 4 hours long on a computer, or 2 GB and 2 hours on a phone. The video is read in pieces rather than loaded into memory, so large recordings work; only the audio file being written has to fit in memory.
192 kbps (High) sounds transparent for most music and is the default. 128 kbps is plenty for speech such as lectures and voice notes. 320 kbps only helps if the source audio is already high quality; it cannot add detail that isn't there.
Related: MKV to MP4 · Video to MP3 · Audio Converter · Transcribe Audio to Text · All tools