AAC to M4A Converter

What happens when you convert AAC to M4A

• The audio is decoded and written as AAC at 192 kbps in an M4A container.
• Going from one lossy format to another adds a small generation loss. Choose a bitrate at least as high as the source to keep it inaudible.

How to convert AAC to M4A online

1. Press "Choose AAC files" and select one or more files, or drag them onto the box. You can add files of any size your device can hold in memory.
2. Adjust the settings if you need to: the bitrate controls quality and size. The defaults suit most people.
3. Press "Convert to M4A". The first audio or video conversion downloads the converter engine, about 32 MB, which your browser then keeps for next time.
4. Save each M4A with its download button. Close the tab and every trace of the files is gone from memory.

Why convert AAC to M4A?

AAC files usually come from iTunes and Apple Music, YouTube audio and streaming. People convert them to M4A because M4A is the native audio format of the iPhone, iTunes and Apple Music.

In short, AAC is good at what it was made for, and M4A is the more practical choice when the file has to play on another device or app. AAC plays in all current browsers and on Apple and Android devices, while M4A plays in all current browsers and every Apple device.

How to convert AAC to M4A on Windows, Mac, iPhone and Android

On Windows

Open this page in Chrome, Edge or Firefox, drag your AAC files in from File Explorer, and press Convert. Each M4A is saved to your Downloads folder. If you prefer a desktop program, VLC can also convert AAC to M4A: choose Media, then Convert / Save.

On a Mac

Safari, Chrome and Firefox all work. Drag the AAC files from Finder onto the drop zone and the M4A files land in Downloads.

On iPhone and iPad

Open the page in Safari and tap Choose AAC files. You can pick from Photos or from the Files app. The converted M4A appears in Files, in the Downloads folder.

On Android

Open the page in Chrome, tap Choose AAC files and pick them from Files or your gallery. The M4A is saved to the Download folder, where any file manager can find it. Keep the screen on while a long video converts, because Android may pause a tab in the background.

Best settings for AAC to M4A

M4A is a lossy format, so the bitrate decides both the sound quality and the file size. Size grows in a straight line with bitrate: double the bitrate and the file doubles.

The AAC was already compressed, so pick a bitrate at least as high as the original. Going higher does not add quality back, it only makes the file bigger.

AAC vs M4A: the differences

About AAC and M4A files

What is an AAC file?

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.

What is an M4A file?

M4A is an MP4 file that only holds audio, which is why renaming one to .mp4 often works. Voice Memos on iPhone saves recordings as M4A.

AAC to M4A not working? Common problems

• The conversion is slow. Audio and container changes take seconds, but re-encoding video runs on your own processor. Lower the resolution to 720p, close other tabs, and keep the device plugged in.
• The tab stops or reloads on a very large file. Browsers limit how much memory one tab can use, around 2 GB and less on phones. Split long recordings or convert them on a computer.
• Song titles are missing. Tags such as title and artist are copied when M4A can store them, but cover art is not carried over.

Convert AAC to M4A with ffmpeg

This converter runs ffmpeg inside your browser. If you would rather use the ffmpeg command line on your own computer, this command produces an equivalent M4A with the same kind of settings:

ffmpeg -i input.aac -vn -c:a aac -b:a 192k output.m4a

Replace input.aac with the name of your file. For a whole folder of AAC files, run the command in a loop, or drop them all on the converter above, which processes them one after another.