Convert MP4 to MP3
We turn MP4 into MP3 right in your browser — the file never goes to a server.
What you will lose
- Surround will be mixed down to stereo — extra channels do not survive this conversion.
How they differ
| MP4 | MP3 | |
|---|---|---|
| Lossless | no | no |
| Lossy | yes | yes |
| Multichannel | yes | no |
| Tags | yes | yes |
| Released | 2001 | 1993 |
| Author | MPEG | Fraunhofer IIS |
MP4
Good at
- Plays on everything: TVs, car stereos, phones a decade old
- Carries several audio tracks, subtitles and chapters in one file
- Streams well: playback starts before the file has finished loading
Awkward about
- Anything can be inside — the extension does not tell you if it will play
- The audio is almost always lossy, so it is not a master copy
- Editing without re-encoding is close to impossible in this container
Use it when
- The video is being sent or published and has to open for everyone
- Footage from a phone that people will simply watch
- One audio track is all you need
MP3
Good at
- Plays literally everywhere, from a 2003 car stereo to a smart speaker
- Predictably small: an hour of speech fits in 30 MB
- Every player reads its tags, without exception
Awkward about
- Lossy, and re-encoding it again is audible
- Two channels at most — surround will not survive
- At the same size, Opus and AAC sound better
Use it when
- It has to open for anyone, on anything
- A podcast, an audiobook, a recorded lecture
- The file goes to a person, not into further processing
Common questions
- Does the file get uploaded to a server?
- Yes, this pair needs the server: browsers cannot encode that format. The file and the result are deleted within a couple of hours and never shared.
- Will surround sound survive?
- No. MP3 reliably carries stereo only, so extra channels are mixed down to two.
- Can I get the original quality back afterwards?
- No. MP3 is lossy, and the discarded detail cannot be recovered. Keep the original if you may still need it.
- How many files, and how large?
- Up to 5 files at a time, 500 MB each. No sign-up, no watermarks.