MP4 to MP3
In your browser, no upload
MP3
video → MP3 · sound re-encoded
Video
MP4 → MP3Specification
7 rows| Item | Value | Notes |
|---|---|---|
| Input | MP4, MOV, WebM | Or any video FFmpeg reads |
| Output | MP3 | Plays on every device, car stereo and app |
| Picture | Left out | Only the sound goes into the file |
| Sound | Re-encoded as MP3 | LAME, variable bitrate, quality 2 |
| Time | Measured before it starts | A 2-second test encode on this device |
| Engine | FFmpeg, 16.8 MB | Browsers carry no MP3 encoder, so FFmpeg is downloaded when you press the button that says so |
| Processed in | This browser | Not sent to a server |
What happens
4What happens, and why
MP3 is the audio format everything still reads — every phone, car stereo, music app and old MP3 player. This page takes the sound out of a video and saves it as an MP3, leaving the picture out. It works for MP4 and MOV from a phone, WebM from a screen recorder, MKV, AVI — anything FFmpeg reads.
Getting an MP3 means encoding. The sound in a video is almost never MP3 — it is AAC in an MP4 or MOV, Opus or Vorbis in a WebM — so it is decoded and encoded again with LAME at variable bitrate, quality 2, which LAME’s own documentation lists at about 190 kbps. That is a second generation of loss on top of the one already in the video, and the badge says so.
If you do not need MP3 in particular, the Extract audio page saves the AAC sound of an MP4 or MOV as an .m4a without re-encoding it at all, which keeps the recording exactly as it was; .m4a plays on any current phone and computer. MP3 is the answer when a device or an app insists on it.
Only the sound is encoded here, which is far less work than a picture. The engine still has to be downloaded first — 16.8 MB, once — and the time is still measured before it starts.
FAQ
4Why not keep the original sound
That is what the Extract audio page does: it copies the AAC in an MP4 or MOV into an .m4a without decoding it. This page exists for when the answer has to be an .mp3, which cannot be had without encoding.
What bitrate is the MP3
It is variable. LAME’s quality 2 setting spends more bits on complex passages and fewer on quiet ones, averaging about 190 kbps for music by LAME’s own table; speech comes out smaller.
Does it work with a video that has no sound
No — there is nothing to save. The page says the file has no sound track rather than writing an empty MP3.
Is the video uploaded
No. The engine is downloaded to your browser, and your file is read and written there. There is no upload endpoint on this site, so there is nowhere for the video to go.