What Is an AAC File?

A file with the AAC file extension is a MPEG-2 Advanced Audio Coding file. It's similar to the MP3 audio format but includes some performance improvements (see them here).

Apple's iTunes and iTunes Music Store use Advanced Audio Coding as their default encoding method for music files. It's also the standard audio format for Nintendo DSi and 3DS, PlayStation 3, DivX Plus Web Player, and other devices and platforms.

Note: AAC files can most definitely use the .AAC file extension but they're more commonly seen wrapped in the M4A file container, and therefore usually carry the .M4A file extension.

You can open an AAC file with iTunes, VLC, Media Player Classic (MPC-HC), Windows Media Player, MPlayer, Audials One, and likely many other multi-format media players.

Tip: You can import AAC files into iTunes through the File menu. On a Mac, use the Add to Library... option. For Windows, choose either Add File to Library... or Add Folder to Library... to add the AAC files to your iTunes Library.

If you need help opening an AAC file in the Audacity audio editing software, see this How to import files from iTunes guide on AudacityTeam.org. You need to install the FFmpeg library if you're on Windows or Linux.

Note: The AAC file extension shares some of the same letters as the extension found in other file formats like AAE (Sidecar Image Format), AAF, AA (Generic CD Image), AAX (Audible Enhanced Audiobook), ACC (Graphics Accounts Data), and DAA, but that doesn't mean they necessarily have anything to do with each other or that they can open with the same programs.

If you find that an application on your PC does try to open the AAC file but it's the wrong application or if you would rather have another installed program open AAC files, see our How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

Use a free audio converter to convert an AAC file. Most of the programs from that list let you convert the AAC file to MP3, WAV, WMA, and other similar audio formats. You can also use a free audio converter to save the AAC file as an M4R ringtone for use on an iPhone.

You can use FileZigZag to convert an AAC file to MP3 (or some other audio format) on macOS, Linux, or any other operating system because it works through a web browser. Upload the AAC file to FileZigZag and you'll be given the option to convert the AAC to MP3, WMA, FLAC, WAV, RA, M4A, AIF/AIFF/AIFC, OPUS, and lots of other formats.

Zamzar is another free online AAC converter like FileZigZag.

Note: Some songs purchased through iTunes may be encoded in a particular type of protected AAC format, and therefore can't be converted with a file converter. See this iTunes Plus page on Apple's website for some information about how you may be able to remove that protection so that you can convert the files normally.