Convert AAC to M4A
Free online converter for AAC files. AAC audio in an MP4 container. Nothing to install, no watermark, and every file is deleted automatically.
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Upload a AAC file to convert it to M4A. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About AAC and M4A
AAC .aac
MP3's designated successor, and the default in the Apple ecosystem and most streaming services. Better sound than MP3 at the same bitrate.
Good for
- Noticeably better than MP3 at equal bitrates
- The default across Apple devices and most streaming
- Handles multichannel audio properly
Trade-offs
- Lossy
- Patent licensing is more involved than Opus or Vorbis
audio/aac
M4A .m4a
An MPEG-4 container holding audio only — usually AAC, sometimes lossless ALAC. The extension tells you the wrapper, not the contents.
Good for
- Rich tagging, including chapters and artwork
- Holds either lossy AAC or lossless ALAC
- The standard for iTunes and Apple Music files
Trade-offs
- The extension alone does not tell you the quality inside
- Support outside Apple platforms is inconsistent
audio/mp4
AAC and M4A side by side
| AAC | M4A | |
|---|---|---|
| Compression | Lossy | Container — usually lossy AAC |
| Typically used for | Streaming, Apple devices, video soundtracks | Apple audio, audiobooks, podcasts |
What changes when you convert AAC to M4A
This is a re-encode, not a repackage
Some tools can move a stream into a different container untouched when the codecs happen to line up. We do not — every job here is decoded and encoded again, so the conversion takes time in proportion to the length of the file and costs a small amount of quality even where a repackage would have been possible. In exchange the output is predictable: it plays everywhere, rather than inheriting whatever the source happened to contain.
What your M4A will contain
The output is AAC — the same codec a bare .aac file holds, wrapped in an MP4 container so that artwork and tags have somewhere to live.
Re-encoding costs a little quality
Both formats are lossy, so this decodes AAC and compresses again as M4A. That second pass loses a small amount on top of what was already gone. It is barely audible once, and it accumulates if a file is converted repeatedly — so convert from the original rather than from a previous conversion.
Tags may not survive intact
AAC stores its metadata as ID3, and M4A uses MP4 atoms. Standard fields such as title, artist and album normally map across. Anything without an equivalent on the other side — unusual custom fields, some ratings and play counts, occasionally embedded artwork — has nowhere to go. Check the tags before deleting the original if your library depends on them.