How to use the MP4 to MP3 converter
- Select the MP4 files or drop the folder that holds them.
- Pick a bitrate: 192 kbps for music, 128 kbps for spoken word, or VBR for a variable rate around 190 kbps.
- Convert to MP3 and save the files, or grab them all as one ZIP.
How the audio is made
Most MP4 soundtracks are AAC, a different codec from MP3, so the track is decoded and encoded again with LAME. Video frames are never decoded, which is why even a long recording finishes quickly. If an MP4 happens to carry MP3 audio already and you change nothing, that track is copied straight across.
A higher bitrate cannot add back what the original lacked. From a 128 kbps AAC soundtrack, 320 kbps MP3 just makes a heavier file; 192 kbps or VBR is a sensible upper limit.
How big the MP3 will be
MP3 size follows bitrate and length alone. Each minute costs just under 1 MB at 128 kbps, close to 1.5 MB at 192 kbps, and a full 320 kbps file needs about 2.4 MB, no matter how heavy the video was. A 45-minute lecture at 128 kbps therefore lands near 43 MB.
For a single speaker, setting Channels to Mono under More settings halves the size at any bitrate with no audible downside.
Whole folders of clips
Drop a folder of lessons or music videos and each MP4 joins the queue. The MP3s keep their original base names, and the ZIP button puts them in one download that is easy to copy onto a phone.
For MOV, MKV, WebM or other formats in the same batch, Video to MP3 accepts them all.
Questions
What if an MP4 has no sound?
That file is marked as having no audio track, and the rest of the queue carries on.
Are my videos sent to a server?
No. Extraction runs inside this browser tab.