MP4 to MP3 — free online tool
MP4 is the format of most videos shot on a smartphone or exported from editing software. This page focuses on that specific case: you drop in an .mp4 file and get its audio back as an MP3, without the picture. Handy for a voice memo shot on video, a narrated presentation or a screen recording with a microphone.
Drop a MP4 file here, or click to choose one
Processed temporarily, deleted afterDrop a MP4 file here, or click to choose one
MP4
How it works
What an MP4 file contains
MP4 is a standardized container (MPEG-4 Part 14). In the vast majority of cases it holds an H.264 video track and an AAC audio track. The tool reads that AAC track, decodes it and re-encodes it as MP3. This is therefore a transcode between two lossy codecs, which is why you cannot get better quality than the original AAC track.
Procedure
Select your .mp4 file, start the conversion and download the MP3 once it is ready. This tool accepts only the MP4 format, which avoids format errors: if your file is a MOV, an MKV or a WebM, use the Video to MP3 page. Processing is fast, because only the audio is encoded and the picture is ignored.
Typical examples
A voice memo recorded as video with the camera, a narrated presentation exported from a slideshow tool, a tutorial whose commentary you want to keep, or the audio of an interview filmed over a video call with the consent of the people involved. In all these cases the MP4 is large while the message fits in a few megabytes of sound.
AAC versus MP3: good to know
At equal bitrate, AAC is generally more efficient than MP3: an AAC at 128 kbit/s often sounds as good as a slightly larger MP3. Converting to MP3 therefore does not improve the sound and may even add a slight loss. The real benefit is compatibility: some older players, car stereos or dictation devices only play MP3.
Practical tips
Check the volume: a smartphone recording made in a noisy environment will stay noisy. If you only need part of it, first trim the video or cut the resulting MP3 with the audio cutter. If the MP4 comes from a platform and already has heavily compressed audio, do not expect studio sound: the source always limits the result.
If the conversion fails
A corrupted MP4, one still being transferred or one from an interrupted capture may be rejected. Check that it plays in a standard player. If the recording has no audio track, like some screen captures, the operation will have no sound to produce. Finally, make sure the extension matches the actual content: a file forcibly renamed to .mp4 can cause problems.
Limitations
Only .mp4 files are accepted on this page. Going from an AAC track to an MP3 is lossy, with no possible improvement of the sound. The tool converts the whole audio track without trimming, and is meant for content you hold the rights to.
Frequently asked questions
What is the difference between this page and Video to MP3?
The engine is the same, but this page is dedicated to MP4 only. If your file is a MOV, MKV, AVI or WebM, the Video to MP3 page is the one you need.
Is MP3 better than the MP4's AAC?
No. AAC is generally more efficient at equal bitrate. MP3's main value is its compatibility with older devices; it never reproduces anything better than the original track.
My MP4 is very large, is that a problem?
Processing will simply take a little longer, because the file has to be uploaded. The picture is ignored during encoding, so the video's resolution barely affects how long the conversion takes.
Can the MP4's metadata be kept?
The tool produces an MP3 containing the audio, with no guarantee of keeping the video's titles or thumbnails. You can fill in the title information in your player or music library afterwards.
Will the sound be synchronized with anything?
An MP3 contains only audio, so synchronization with the picture no longer applies. Keep the original if you will need to put the picture back together with the sound.
Am I allowed to convert any MP4?
Only those you hold the rights to or have permission to use. Extracting the music from a protected work without a license is prohibited in most countries.