How to convert M4A to MP3
- 1
Add the recording
Choose an M4A or AAC file, or drag it onto the box above. - 2
Pick a quality
Choose 128, 192 or 320 kbps. 192 kbps is selected by default and suits most recordings. - 3
Convert and download
Press Convert to MP3. The MP3 keeps the name of your recording and runs just as long.
Why your phone gives you an M4A file
M4A is the format many phones and recording apps save to, including Voice Memos on the iPhone. It holds AAC audio, which is compact and sounds good, but some older car stereos, dictation programs and upload forms only accept MP3. That is when you need this converter.
If a form or program does accept M4A, keep the M4A. Each conversion encodes the sound again, so the original is always the better copy. The tool does not change your M4A file.
Which quality suits a recording?
- 128 kbps is plenty for an interview or a voice memo, at about 58 MB per hour.
- 192 kbps leaves a margin if the recording has several speakers or background sound, at about 86 MB per hour.
- 320 kbps only pays off for music, at about 144 MB per hour.
A higher bitrate than the M4A itself rarely helps. A voice memo at 64 kbps will not sound better as a 320 kbps MP3, only larger. Recordings with a low sample rate have a lower ceiling: at 16 kHz the MP3 format stops at 160 kbps, and the encoder uses the nearest bitrate it allows.
Privacy and limits
Interviews and voice memos are often private, so the conversion happens in your browser and the recording is not uploaded. The MP3 stays in memory until you save it, and it can be up to 1 GB, which is about 11 hours at 192 kbps.
It works in current Chrome and Safari on a computer. On a phone it depends on the browser and the free memory, so try a short file first. Tracks bought with copy protection cannot be read.
Do you need the words rather than the sound? Upload the recording to Spirelight transcription for a draft with speakers and timestamps, which you check against the audio yourself.