MP4 to MP3 converter

1. 1

   Add an MP4

   Any MP4 with sound works, from a phone, a camera, an editor export or a screen recording.

2. 2

   Pick a bitrate

   128 kbps for speech, 192 kbps for most music and mixes, 320 kbps when you want the highest MP3 quality.

3. 3

   Convert and download

   Play the MP3 to check it, then download it.

The bitrate sets both the sound and the size. MP3 here is constant bitrate, so the size depends only on length:

• 128 kbps, about 1.0 MB a minute: voiceovers, talking-head clips, podcasts.
• 192 kbps, about 1.4 MB a minute: music, background tracks, mixed audio.
• 320 kbps, about 2.4 MB a minute: the highest MP3 allows, for music you'll edit or keep.

The sound in an MP4 is almost always AAC, which is already compressed. Converting it to MP3 decodes it and compresses it again, so the MP3 is at best as good as the MP4's audio. Choosing 320 kbps for an MP4 whose audio is 128 kbps makes a bigger file, not a better one.

If the app you're sending to accepts M4A, the extract audio tool copies the AAC out with no second encode at all. To see what's in your MP4, ffprobe prints the audio codec and bitrate:

• ffprobe -v error -select_streams a -show_entries stream=codec_name,bit_rate -of default=noprint_wrappers=1 input.mp4

The same conversion on the command line. -vn drops the video:

• ffmpeg -i input.mp4 -vn -c:a libmp3lame -b:a 192k audio.mp3
• Only seconds 2 to 5: ffmpeg -i input.mp4 -vn -ss 2 -to 5 -c:a libmp3lame -b:a 192k part.mp3

No. Your browser reads the video and encodes the MP3 itself, with the LAME encoder running on your computer. Nothing is sent anywhere.

No. MP3 is lossy, and the MP4's AAC audio was lossy too, so converting adds a second round of compression.

The same as the MP4's audio, usually 48 kHz for phone and camera video or 44.1 kHz for music exports. The tool shows it once it's done.

The tool converts the whole file. To cut a clip, use the ffmpeg command above with -ss and -to, or trim the MP3 afterwards in any audio editor.