Convert video to MP3
Pull the soundtrack out of any video and save it as MP3 with a bitrate you choose. Optional trim, instant preview, nothing uploaded.
- Runs in your browser
- Files are never uploaded
- Free, no account
First use downloads the 10 MB video engine from this site. After that it is cached and works offline. It is WebAssembly served from onthisdevice.com — no third-party CDN — and your file is still processed entirely on your own device.
How to convert a video to MP3
- Drop the video in — MP4, MOV, MKV, WebM, AVI and more are all read by FFmpeg.
- Pick a bitrate. 192 kbps is the default and is transparent for most music; 96 kbps is plenty for speech.
- If you only want part of the soundtrack, switch on Trim before extracting, then drag the handles or type exact timecodes.
- Press Extract MP3. The estimated size updates as you change the settings, so there are no surprises.
- Play the result in the built-in player and download it.
Choosing a bitrate
MP3 bitrate is a straight trade between size and fidelity. The figures below are for stereo audio; mono halves them.
| Bitrate | Per minute | One hour | Sounds like |
|---|---|---|---|
| 320 kbps | 2.4 MB | 144 MB | The MP3 ceiling — keep for music you will re-edit |
| 256 kbps | 1.9 MB | 115 MB | Very good; the difference from 320 is hard to hear |
| 192 kbps | 1.4 MB | 86 MB | Recommended default for music |
| 128 kbps | 0.9 MB | 58 MB | Fine on phone speakers, thin on headphones |
| 96 kbps | 0.7 MB | 43 MB | Speech, lectures, podcasts |
Generation loss, and how to avoid it
The soundtrack inside an MP4 is almost always AAC, which is already lossy. Re-encoding it to MP3 is a second lossy pass, so a little detail disappears — mostly in cymbals, sibilance and room reverb. Choosing a higher bitrate limits the damage but cannot undo the first pass.
If you want the audio exactly as it exists inside the video, use
extract audio from video in stream-copy mode instead:
it lifts the AAC track out untouched into an .m4a file. Convert to MP3 only when
something in your workflow specifically needs MP3.
Common uses
- Lectures and webinars — 96 kbps mono turns a 1 GB screen recording into a file you can listen to on a walk.
- Interviews for transcription — most transcription apps take MP3 happily and charge by minute, so trim first.
- Music from your own recordings — pull the audio from a camera recording of a rehearsal.
- Voice notes — extract, trim to the useful part, and keep the file small enough to email.
Privacy
The conversion happens in this tab using FFmpeg compiled to WebAssembly. Your video is never uploaded, so interviews, medical recordings and unreleased material stay on your machine. You can confirm it by going offline after the engine has loaded once — everything still works.
Questions
Which bitrate should I choose?
192 kbps is transparent for most music and is the default here. Use 320 kbps if you want the maximum MP3 quality, and 96 kbps for speech — a one-hour talk is then about 43 MB.
Can I export only part of the video?
Yes. Turn on "Trim before extracting" and drag the two handles, or type exact times. FFmpeg seeks to the start point before decoding, so trimming also makes the export faster.
Does converting to MP3 lose quality?
Some, unavoidably. The video soundtrack is already lossy (usually AAC), and re-encoding it to MP3 is a second lossy pass. If you want a bit-perfect copy, use the extract-audio tool in stream-copy mode instead.
The video has no sound — what happens?
FFmpeg reports that no audio stream matched and the tool tells you so in plain language rather than handing you an empty file.