- To begin, you have to make sure iTunes is set to create MP3 files (its encoding functions allow you to create many kinds of files, including AAC, MP3, and Apple Lossless). To do this, you'll need to open the Preferences window. On Windows do this by going to Edit -> Preferences. On a Mac go to iTunes -> Preferences.
- In the Preferences window that pops up, click the "Import Settings" button towards the bottom of the General tab. You'll find it next to the "When you insert a CD" drop-down box.
- In the Import Settings window that pops up, choose MP3 Encoder from the "Import Using" drop-down. You'll also want to choose something in the "Setting" menu. The higher the quality setting, the better the converted song will sound. I'd recommend 192 kbps or 256 kbps, and certainly nothing lower than the current bit rate of the AAC file to be converted. When you're happy with your settings, click "OK." Click "OK" in the Preferences window to close that.
- Next, find the song or songs you're converting from AAC to MP3 in iTunes. You can select songs one at a time, in a group by using Control-A on Windows and Command-A on a Mac, or in a group of non-contiguous files by holding down Control (on Windows) or Command (on Mac) while you click each file.
When you've selected all the files you want to convert from AAC to MP3, you have two choices for how to begin the conversion:
- Click on the File menu in iTunes, then Create New Version, and select "Create MP3 Version", OR
- Right click on the selected files and choose "Create MP3 Version" from the pop-up menu.
When you click on one of those options, the conversion will begin. How long it takes will depend on how many songs you're converting and the conversion settings.
- When the conversion from AAC to MP3 is complete, you'll have two copies of each converted file, one in AAC, the other in MP3. You may be happy to have both copies. If not, though, and you want to delete one, you'll need to know which is which. In that case, select the file you're curious about and hit Control-I on Windows or Command-I on a Mac. This will pop up the song's information window. The Kind field will tell you whether the song is an AAC or MP3.