Convert MP4 to MP3
Extract the soundtrack from MP4 video as an MP3 at up to 320 kbps. Queue as many files as you like — every one is decoded on your own device.
- 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 pull the audio out of an MP4
- Drop one file or fifty onto the box above.
- Pick a bitrate. 192 kbps suits music; 128 kbps or mono is plenty for speech.
- Press extract. Each file gets its own progress bar and its own download button.
- With more than one result, take them all at once as a ZIP.
Choosing a bitrate
| Bitrate | Size per hour | Good for |
|---|---|---|
| 320 kbps | ~137 MB | Music you will listen to on decent headphones |
| 256 kbps | ~110 MB | Music, effectively transparent |
| 192 kbps | ~82 MB | The default — good for almost everything |
| 128 kbps | ~55 MB | Podcasts, lectures, background listening |
| 96 kbps mono | ~41 MB | Interviews and voice notes for transcription |
The honest bit about quality
An MP4 normally carries AAC audio, which is already lossy. Converting it to MP3 compresses the decoded result a second time, and no setting can recover detail the first pass threw away. That is called generation loss, and it is a property of the formats, not of this tool.
In practice it is inaudible at 192 kbps and above on nearly all material. If you want to avoid the second compression entirely, extract to M4A instead with the audio converter — an M4A extraction can copy the AAC stream out of the video untouched, which is genuinely lossless. Choose MP3 when you need something that plays on a car stereo, an old MP3 player or a piece of software from 2009; choose M4A when quality is the priority.
Why a batch queue matters here
Upload-based converters ration this operation because each conversion costs them CPU time and bandwidth: Smallpdf-style task meters, "3 files per hour", "sign up to convert more than 25". Running locally, the marginal cost of the twentieth file is your own electricity, so there is no counter, no account and no per-day limit. Queue an entire lecture series and walk away.
What is not included
- No ID3 tags. The MP3 comes out clean, with no title, artist or album written into it — and equally, no stray metadata carried over from the source video.
- No normalisation. The loudness of the source is preserved exactly, so a quiet recording stays quiet.
- No trimming. If you need part of the audio, extract first and then use trim audio.
- One audio track. If the MP4 carries several languages, the first is used.
A note on what you convert
This tool runs on your machine and asks nothing about your file, but the law still applies to you: extracting audio from something you bought or recorded is your business, and doing it to redistribute somebody else’s work is not. Nothing about local processing changes that.
Questions
Does converting to MP3 lose quality?
A little, unavoidably. MP4 video normally carries AAC audio, and turning AAC into MP3 is a second lossy compression — you cannot recover what the first one discarded. At 192 kbps the difference is inaudible on most material; at 320 kbps it is inaudible on all of it. If you want no second loss at all, extract to M4A instead with the audio converter.
Which bitrate should I choose?
For music, 192 kbps is the sweet spot and 320 kbps is the safe maximum. For a lecture, podcast or interview, 128 kbps or even 96 kbps mono halves the file with no practical downside — speech simply does not need the bandwidth.
Can I convert several videos at once?
Yes. Drop in as many as you like and they run one after another with a progress bar each, then download individually or as a single ZIP. There is no per-day cap, because there is no account and no server keeping count.
Does it keep the artist and title tags?
No. The MP3 is written with no ID3 metadata at all, which also means no stray tags from the source file travel with it. Add tags afterwards in your music player if you need them.