How to convert AAC to MP3 on Windows

The AAC to MP3 converter works in Chrome, Edge, Firefox, Brave — any modern browser on Windows. It decodes your AAC file using the browser's built-in audio engine and re-encodes it to MP3 with a JavaScript-based LAME encoder running in a Web Worker.

Because everything runs client-side, there is no file-size cap enforced by a server, no queue, and no wait time. A 100 MB audiobook chapter converts just as easily as a 3 MB voice recording. You can convert up to 20 files per batch — drag them all at once or add them one by one.

This is the best option if you need a quick conversion without installing anything. If you convert files regularly or need to process hundreds of files at once, the desktop methods below give you more automation.

VLC is free, open-source, and already installed on many Windows PCs. It can convert audio formats, though the option is buried in the menus.

1. Open VLC and go to Media > Convert / Save (or press Ctrl+R).
2. Click Add and select your .aac or .m4a files. Click Convert / Save.
3. In the Profile dropdown, select Audio – MP3. If you need a specific bitrate, click the wrench icon to open profile settings and set it under Audio codec > Bitrate.
4. Choose a destination file and click Start. VLC encodes the file and saves the MP3.

VLC works well for one-off conversions but does not support batch output to separate files easily. For multiple files, the browser converter or ffmpeg is faster.

ffmpeg is the gold standard for audio and video conversion. It is free, open-source, and runs on every version of Windows. Install it via winget install ffmpeg in PowerShell, or download the binaries and add them to your PATH.

To convert a single file:

ffmpeg -i input.aac -codec:a libmp3lame -b:a 192k output.mp3

To batch-convert every .aac file in a folder (PowerShell):

Get-ChildItem *.aac | ForEach-Object {
  ffmpeg -i $_.Name -codec:a libmp3lame -b:a 192k ($_.BaseName + ".mp3")
}

Replace 192k with 256k or 320k for higher quality. For .m4a files, swap *.aac with *.m4a — the rest of the command stays the same.

ffmpeg is the best choice when you have hundreds of files or want to script conversions into an automated workflow. For everything else, the browser converter is simpler. See the batch conversion guide for more details on large-scale conversion.

The most common source of AAC files on Windows is iTunes (or the Apple Music app on Windows 11). Purchased songs are DRM-free .m4a files at 256 kbps AAC, stored by default in:

C:\Users\YourName\Music\iTunes\iTunes Media\Music

Apple Music streaming tracks are DRM-protected and cannot be converted by any tool. If a file fails to load in the converter, it is likely a protected stream rather than a purchased track.

To find all AAC files on your PC, open File Explorer and type *.aac OR *.m4a in the search bar. You can then select the files you want and drag them directly into the browser converter.

For a full explanation of why AAC-to-MP3 conversion affects quality and how to minimize the loss, read the quality-loss guide. For a broader comparison of the two formats, see AAC vs MP3.

Most desktop AAC-to-MP3 converters for Windows are ad-supported, bundle unwanted toolbars, or require a paid license for bitrates above 128 kbps. Some upload your audio to a remote server for processing.

A browser converter avoids all of that. There is nothing to install, nothing to uninstall, no registry entries, and no background process. Your audio stays on your PC because the encoding happens in a Web Worker inside your browser. And because there is no server involved, there is no file-size limit, no queue, and no daily conversion cap.