Convert MP4 to MP3 in your browser
Drop an MP4 file, pick an MP3 bitrate and download the audio track. The conversion runs on your own device, so the video is never uploaded anywhere.
How it works
- 1
Choose or drop the MP4 file you want to turn into audio.
- 2
Keep the default MP3 at 192 kbps or pick 128, 256 or 320 kbps.
- 3
Click MP4 to MP3, then download your MP3. Nothing left your device.
What is inside an MP4 file
MP4 is a container: one file that holds a video stream, one or more audio streams and some metadata. In almost every MP4 you will meet, from phone cameras, screen recorders, video editors or downloaded clips, the audio is stored as AAC. That audio is already compressed, so an MP4 to MP3 conversion decodes the AAC track and encodes it again as MP3 with the LAME encoder.
The video stream is simply ignored. That is why the MP3 is so much smaller than the MP4: a ten-minute 1080p video can weigh several hundred megabytes, while its soundtrack as a 192 kbps MP3 takes about 14 MB.
Which MP3 bitrate should you choose?
The bitrate decides how many bits describe each second of sound. Higher means more detail and a bigger file. As a rule of thumb, one minute of audio takes about 1 MB at 128 kbps, 1.4 MB at 192 kbps, 1.9 MB at 256 kbps and 2.4 MB at 320 kbps.
128 kbps is fine for speech: lectures, interviews, voice notes, audiobooks. 192 kbps, the default, is a good all-round choice that most people cannot tell apart from the original on phones and earbuds. 256 or 320 kbps make sense for music you want to keep, or when you will edit the file later.
One thing a high bitrate cannot do is add quality that was not there. If the MP4 carries AAC audio at 128 kbps, a 320 kbps MP3 will be larger but will not sound better than the source. When the soundtrack matters, start from the best MP4 you have.
Why convert MP4 to MP3 at all?
MP3 plays on everything: old car stereos, MP3 players, smart speakers, every phone and every audio app. It is the safest format when you want to listen to a talk on the go, keep a concert recording, send a voice track to someone, or load a song into a device that does not accept video files.
If you only need the audio for editing and your MP4 already contains AAC, the Extract Audio tool can copy that track to M4A without re-encoding. For an uncompressed file, MP4 to WAV gives you 16-bit PCM.
Private, fast and without a size cap from us
Vidmini decodes the MP4 with your browser's WebCodecs API and encodes the MP3 with a WebAssembly build of LAME, all on your computer or phone. The page is not allowed to send your file anywhere: once it has loaded, you can even go offline and it keeps working.
There is no file size limit set by us. The output is written to your browser's private storage, so desktop browsers handle long, multi-gigabyte MP4 recordings. On phones, free memory and storage set the practical limit.
Frequently asked questions
Is this MP4 to MP3 converter really free?
Yes. There is no account, no watermark, no paid tier and no daily quota. The conversion uses your own device, which is why it costs us nothing to run.
Does converting MP4 to MP3 lose quality?
A little, because the AAC audio in the MP4 is decoded and encoded again as MP3. At 192 kbps or more the difference is very hard to hear. If you want no loss at all, use Extract Audio to copy the AAC track to M4A as it is.
Can I convert an MP4 from my iPhone or Android phone?
Yes. Open the page in Safari, Chrome, Edge or Firefox on your phone and select the video from your gallery or files. Long videos need enough free memory and storage on the phone.
What if my MP4 has no sound?
Some MP4 files, such as certain screen captures or GIF exports, contain no audio track at all. In that case there is nothing to convert, and Vidmini tells you the file has no audio.
Can I convert several MP4 files at once?
Vidmini handles one file at a time. Each conversion is quick, and you can start the next one as soon as the download is done.
Is my video uploaded to a server?
No. The MP4 is read and converted by your browser on your device. Our Content Security Policy only lets the page talk to vidmini.com for its own code, and no tracking cookies are used.