What is an AAC file?
AAC stands for Advanced Audio Coding. It was created by the Moving Picture Experts Group and first released in 1997. AAC was designed as the successor to MP3 and sounds better at the same bitrate, especially below 128 kbps. A bare .aac file is a raw stream with no chapters or cover art; the same audio in a container is usually called M4A.
| Type | audio |
|---|---|
| Compression | Lossy |
| Usually contains | AAC audio in a raw ADTS stream |
| In a browser | plays in all current browsers and on Apple and Android devices |
| Common uses | iTunes and Apple Music, YouTube audio and streaming |
| MIME type | audio/aac |
Which format should you convert AAC to?
- AAC to MP3 to play on any device, car stereo or website.
- AAC to M4A for iPhone, iTunes and Apple Music.
- AAC to WAV to edit in an audio editor or burn to CD.
- AAC to FLAC to archive without losing any quality.
- AAC to MP4 to upload somewhere that only accepts video.
AAC is already lossy, so converting it to a lossless format makes the file bigger without improving it; pick a lossless target only if a program requires one.
How to open an AAC file
Whether an AAC file opens with a double click depends on the device. Here is what works on each, without buying software:
| Windows | Films and TV and Media Player open the common formats; VLC opens almost any audio file, AAC included. |
|---|---|
| Mac | QuickTime Player opens formats Apple supports; VLC or IINA open the rest. |
| iPhone and iPad | The Files app plays formats Apple supports. For others, a player such as VLC for iOS, or converting the file here, is the easiest route. |
| Android | Most gallery and music apps play the common formats; VLC for Android plays almost everything. |
| Web browser | AAC plays in all current browsers and on Apple and Android devices. |
Want the technical details? See what a .aac file is, with its MIME type, file signature and a viewer.
AAC compared with other audio formats
How AAC stacks up against the formats people most often convert it to or from:
| Format | Compression | Usually contains | Released | Best for |
|---|---|---|---|---|
| AAC | Lossy | AAC audio in a raw ADTS stream | 1997 | iTunes and Apple Music, YouTube audio and streaming |
| MP3 | Lossy | MP3 audio, typically 128 to 320 kbps | 1993 | music libraries, podcasts and anything that has to play everywhere |
| WAV | Lossless | uncompressed PCM, usually 16-bit at 44.1 or 48 kHz | 1991 | recording, editing, sound effects and CD audio |
| M4A | Either | AAC, or ALAC for lossless files | 2001 | iTunes purchases, iPhone voice memos and Apple Music downloads |
| FLAC | Lossless | FLAC lossless audio, up to 32-bit and 655 kHz | 2001 | CD rips, hi-res music stores and audio archives |
How to use the AAC converter
- Choose the format you want in the Convert to menu.
- Drop your AAC files on the box, or press Choose AAC files. Several files can go in at once.
- Adjust the settings if you need to; the defaults suit most people.
- Press Convert and save each file with its Download button. Nothing is uploaded at any point.
Tips for converting AAC files without losing quality
AAC is lossy, so some detail was already discarded when the file was made. Converting it cannot bring that back. Converting to a lossless format preserves what is left exactly but makes the file larger; converting to another lossy format adds a small extra loss, which is invisible at sensible settings.
- Keep a lossless master. If you have WAV, FLAC, AIFF or ALAC, keep it, and make lossy copies such as MP3 or AAC from it when you need them.
- Avoid converting one lossy format into another more than once. Each MP3, AAC or OGG encode throws away a little more, and the losses add up.
- Match the bitrate to the content: 192 kbps and up for music, 96 to 128 kbps for podcasts, 64 kbps for voice notes.
- Stick to 44.1 kHz for music and 48 kHz for audio that goes with video; resampling between them is harmless but pointless.
Convert AAC files from the command line
Everything this page does can also be done in a terminal. The most common AAC conversion, to MP3, looks like this with ffmpeg:
ffmpeg -i input.aac -vn -c:a libmp3lame -b:a 192k output.mp3Change the output extension to pick another format. The converter above runs the same ffmpeg engine inside your browser, so you get the result without installing anything.
AAC converter FAQ
What is an AAC file?
AAC stands for Advanced Audio Coding, an audio format created by the Moving Picture Experts Group in 1997. AAC was designed as the successor to MP3 and sounds better at the same bitrate, especially below 128 kbps. A bare .aac file is a raw stream with no chapters or cover art; the same audio in a container is usually called M4A.
How do I open an AAC file?
AAC plays in all current browsers and on Apple and Android devices. If the program you need will not open it, convert it to a more widely supported format above.
What is the most common AAC conversion?
AAC to MP3 is the conversion people search for most. The audio is decoded and written as MP3 at 192 kbps.
Does converting AAC files here upload them?
No. Every conversion on this page runs inside your browser, so your AAC files never leave your device.
Is the AAC converter free?
Yes. There is no sign-up and no watermark, and no limit on how many AAC files you convert. The site is supported by advertising.
Can I convert AAC files on iPhone or Android?
Yes. Open this page in Safari on iPhone and iPad, or in Chrome on Android, choose your AAC files and download the results to your Downloads folder.
Can I convert several AAC files at once?
Yes. Drop as many as you like; they are converted one after another, each with its own download button.