AAC to M4A Converter
Convert AAC to M4A free — no upload, no signup
To convert AAC to M4A, drop your AAC audio files into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. AAC audio is repackaged into M4A with no re-encoding.
Drop audio files here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
Advanced
How to convert AAC to M4A
Add your AAC files
Drag and drop AAC files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Pick a bitrate
192 kbps suits music and 128 kbps or less suits speech. Sample rate and mono/stereo are under Advanced.
Convert and download
Click Convert, then download each M4A file or all of them as one ZIP.
Why convert AAC to M4A?
M4A adds what raw AAC lacks: proper seeking, duration and tag support, so files behave nicely in iTunes, phones and players.
What happens when you convert AAC to M4A?
Because M4A uses AAC too, Fylo simply moves the audio into an MP4 container — no quality loss, near-identical size, done in seconds.
How does Fylo convert AAC to M4A?
Fylo decodes the AAC audio in the AAC with ffmpeg compiled to WebAssembly and encodes it with FFmpeg's AAC encoder at 160 kbps inside an MPEG-4 (M4A) container. Both formats are lossy, so each conversion discards a little detail — start from the highest-bitrate AAC you have. A 3-minute song is ≈ 3.6 MB at 160 kbps as AAC and ≈ 3.6 MB at 160 kbps as M4A. The original sample rate and channel layout are kept unless you change them under Advanced.
What's the difference between AAC and M4A?
AAC (Advanced Audio Coding) was standardised in 1997 as part of MPEG-2 and later MPEG-4, designed to replace MP3. It achieves better quality at the same bitrate, especially below 128 kbps. A .aac file is usually a raw ADTS stream; the same audio inside an MP4 container is called M4A.
M4A is an MPEG-4 container that holds only audio — usually AAC, or Apple Lossless (ALAC). Apple popularised the extension with the iTunes Store in 2003; iPhone Voice Memos and many podcasts also use it. Audiobooks often use the related .m4b extension.
Learn more: AAC format guide · M4A format guide
| Property | AAC | M4A |
|---|---|---|
| Compression | Lossy | Lossy (AAC) or lossless (ALAC) |
| Typical bitrate | 96–256 kbps | 128–256 kbps |
| 3-minute song | ≈ 3.6 MB at 160 kbps | ≈ 3.6 MB at 160 kbps |
| Tags and cover art | Limited in raw .aac (full in M4A) | Yes (full, with cover art) |
| Compatibility | Very wide: Apple, Android, YouTube, browsers | Apple devices, Android, Windows 10+, browsers |
| Best for | Efficient music and video soundtracks | iTunes/Apple Music libraries, voice memos, audiobooks |
| Introduced | 1997 | 2003 |
Frequently asked questions
Is AAC to M4A lossless?
Yes, when settings are left at their defaults the audio is copied, not re-encoded.
Why does my M4A show the correct length now?
Raw AAC streams have no duration header; M4A includes one.
Is my AAC file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your AAC file is read directly from your device and never sent anywhere.
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