How to Convert MP4 to MP3 (and When to Keep M4A)

You want the soundtrack of a video you recorded, the audio of a lecture for your commute, or a voice memo out of a screen recording. Converting MP4 to MP3 takes a minute, and there are a few choices that affect quality and size.

What's inside an MP4

An MP4 file is a container. It usually holds a video stream (often H.264 or H.265) and an audio stream, almost always AAC. Converting to MP3 means decoding the AAC audio and encoding it again as MP3, dropping the video entirely.

Convert in the browser

1. Open the MP4 to MP3 converter.
2. Drop your video. Large files are fine, since they're read in pieces and nothing is uploaded.
3. Choose a bitrate:
   • 128 kbps for speech, podcasts and lectures,
   • 192 kbps for music (the default, transparent for most listeners),
   • 256–320 kbps if you want to be safe for critical listening.
4. Convert and download the MP3.

MOV, MKV and WebM videos work the same way.

Only a part of the video?

The extract audio tool lets you set a start and end time, so you don't have to convert a two-hour recording to get one song. It saves the audio as the original stream (no re-encoding), WAV, M4A or Opus, and shows the waveform of the result. If you need MP3 specifically, convert the extracted file afterwards.

MP3 or M4A?

Each re-encoding with a lossy codec loses a little quality. Going from AAC to MP3 is one such step. Alternatives:

• M4A holds AAC audio, the same as in the video. Choosing Original in the extract audio tool keeps the audio stream as it is, without re-encoding: faster and without any quality loss. M4A plays on iPhones, Macs, Android, Windows and in most car systems.
• MP3 is the choice when a device or app accepts nothing else, such as older MP3 players and some car radios or editing tools.
• WAV is uncompressed and large, useful when you want to edit the audio further.

Checking the result

Open the file in the audio waveform viewer to see the waveform and spectrogram and measure loudness. A spectrogram shows the frequency range. A cutoff around 16 kHz is typical for 128 kbps files and nothing to worry about for speech.

A note on rights

Converting a video you recorded yourself, or one you have permission to use, is fine. Downloading and converting copyrighted music or videos from streaming platforms may break their terms of use and copyright law, depending on where you live.

Frequently asked questions

Does the MP3 sound better at 320 kbps than the original video? No. The result can't be better than the audio inside the MP4. If the video's AAC track was 128 kbps, a 320 kbps MP3 just makes the file larger.

Can I convert several videos at once? Yes. Drop multiple files into the converter; each is converted with the same settings, and you can download them all as a ZIP.

What about videos from my phone? iPhone videos are usually MOV files, Android videos MP4. Both work the same way. Slow-motion and 4K videos take a little longer because the whole file has to be read, but only the audio is processed.

Why is the MP3 so much smaller? Video takes up almost all of an MP4's size. A minute of 192 kbps MP3 is about 1.4 MB, whatever the video resolution was.