"Hi, I'm currently looking for a converter that I can use to convert from MP3 to AAC 'cause I need AAC file for edit. Where can I find such a converter? And a converter that could work on both Windows and Mac OS would be great."

Use Professional MP3 to AAC Converter Mac and Windows Version to Convert MP3 to AAC Mac & Windows

There aren't that much of MP3 to AAC converters that could work on both Windows and Mac OS, usually companies and developers like to take sides, no matter it's Windows or Mac OS. But there are still converters that have both Windows and Mac OS version. Leawo Video Converter is one of the best audio and video converters that has developed not only the Windows version but also the Mac OS version.

The steps of Using Leawo Video Converter to convert MP3 to AAC on both Windows and Mac OS are pretty much the same, so in the following content the guidances of Windows and Mac OS converting MP3 to AAC will be shown together.

Step 1: Import source MP3 file

Run Leawo Video Converter, click Video Converter tag to enter the conversion section. The first thing to do is to add the source MP3 file to the interface. To do so, click the Add File button or drag the source file directly to the interface.

Load source files
Load source files

Step 2: Set AAC as output format

The second step is to set output format. Move your mouse over the button on the left of the big green Convert button, click it to call out a drop-down box. And then click Change button in the middle to enter the "Profile" panel. Go to Format>Common Audio and select AAC as the default output format.

Choose format
Choose format

Note:

Audio parameters like Audio Codec, Sample Rate, Bit Rate, Channel are editable in the Profile Settings panel. To enter Profile Settings panel, click the Edit button on the previous drop-down menu or click the Edit button on the format tag while you were choosing format in the Profile panel.

Set detailed parameters
Set detailed parameters

Step 3: Start MP3 to AAC conversion/

Go back to the main interface, click the big green Convert button and a sidebar would show up, set the output directory for the output AAC file at the top and then click the Convert button at the bottom to start the conversion.

Start converting
Start converting

Use Free Audio Converter to Convert MP3 to AAC Mac & Windows

There's an MP3 to AAC converter free of any charges and supports Windows and OS X. MediaHuman Audio Converter is a freeware audio converter for converting various formats of videos and audios into other audio formats.

MediaHuman Audio Converter

  • Simple and straightforward interface
  • Converts between all popular audio formats
  • Splitting tracks by CUE sheet
  • iTunes support
  • Converts multiple files simultaneously
  • Keeps folder structure
  • Extracts audio track from video
  • Totally Free

The guide below shows you how to convert MP3 to AAC on Mac and Windows using MediaHuman Audio Converter

Step 1: Run MediaHuman Audio Converter, import the MP3 file you want to convert to the interface by dragging them directly to the interface or clicking the "+" button to choose from your computer.

Add file
Load source files

Step 2: Choose MP3 as the default output format in the format box.

Choose Format
Choose format

Step 3: Go to Settings and set the directory for the output file, go back to the main interface and click Start button to start the conversion.

Output directory
Settings

Use iTunes as An MP3 to AAC Converter Mac and Windows Version to Convert MP3 to AAC Mac & Windows

Actually iTunes can also be used as an MP3 to AAC converter Mac & Windows version. What's great about iTunes is that it has both OS X version and Windows Version. To convert MP3 to AAC Mac and Windows users could give this a shot.

To convert MP3 to AAC iTunes just needs a few steps. Below is the guide to use iTunes to convert MP3 to AAC Mac&Windows:

Step 1: Open iTunes Preferences: Choose "iTunes>Preferences>General" tab.
Step 2: Move mouse to Importing Settings… button in the lower section of the window and click it. 
Step 3: From the Import Using pop-up menu, choose AAC Encoder as the encoding format, then click OK to save the settings.
Step 4: Back to the audio list panel, select one or more songs in your library, then from the "File>Create New Version" menu, choose "Create AAC Version". iTunes would then quickly convert MP3 to AAC format.