M4A to AAC Converter — Free, Online, No Upload

M4A and AAC are the same audio codec in different packaging. An M4A file is simply an MP4 container with an AAC audio track inside — the audio data is identical. The distinction only matters when a piece of hardware or software cares about the container rather than the codec. Most consumer apps handle both interchangeably, but certain systems do not.

Broadcast delivery systems, smart TV apps, automotive infotainment systems, and some embedded media players are built to read raw AAC bitstreams (.aac files) rather than MP4-wrapped containers (.m4a files). If you're delivering audio to a DAB+ radio system, an HLS streaming pipeline that ingests bare AAC, or a device that parses codec headers strictly, a raw .aac file is what the system expects. The conversion is a container remux — the audio data inside is extracted and written to the new format without any re-encoding, so there is no quality change whatsoever.

The resulting AAC file will be virtually the same size as the M4A source. The audio quality is bit-for-bit identical. What changes is the wrapper — from an MP4 container to a raw AAC bitstream. A raw .aac file can't hold tags or album art, so those stay behind in the M4A.

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

AAC output is encoded at 192 kbps.

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