AAC to M4A Converter — Free, Online, No Upload

AAC and M4A contain identical audio — the difference is the wrapper. A raw .aac file is a bare AAC bitstream; an .m4a file is the same audio tucked inside an MPEG-4 container. The distinction is purely structural, but it has real consequences: iTunes ignores raw .aac files, Apple Music won't import them, and the iOS Music app won't play them. The MP4 container that M4A uses is what enables rich metadata, embedded album art, and the chapter markers that podcasts rely on.

If you have .aac files downloaded from a streaming tool, extracted from a broadcast system, or generated by audio processing software, converting them to M4A is the step that makes them visible and playable in the Apple ecosystem. The process is a container remux — the audio data is extracted from the raw AAC bitstream and wrapped in an MP4 container without any re-encoding. Quality is bit-for-bit identical to the source; file size changes are negligible.

The resulting M4A file will work in iTunes, Apple Music, GarageBand, Logic Pro, QuickTime, and on every iPhone and iPad without any additional software. It will also be accepted by podcast hosting platforms like Buzzsprout, Anchor, and Apple Podcasts Connect. AirPlay, CarPlay, and HomePod playback all work natively with M4A. No quality is lost in the process.

Typical sizes (3-minute song): AAC 2–5 MB → M4A 3–6 MB.

M4A output is encoded at 192 kbps.

Re-encoding one lossy format into another adds a second round of compression.