Step 1: Provide your AAC files using the button above or by toss and let go.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Fetch your converted M4A files.
AAC to M4A Conversion FAQ
What bitrate does the M4A file end up at?
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A lossy M4A is encoded at 192 kbps by default. The Audio Quality setting also offers 320 kbps for the best quality and 128 kbps for a smaller file. A lossless M4A (WAV, FLAC) ignores the bitrate and keeps every sample.
Is converting AAC to M4A a second round of lossy compression?
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Yes, and it is worth planning around. Both formats are lossy, so the M4A encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the M4A from that instead avoids the double pass entirely. AAC is lossy but more efficient than MP3, and it handles up to 48 channels natively rather than being bolted onto a stereo design. An M4A holds AAC in most cases, or Apple Lossless (ALAC) when it came from a lossless rip.
Will going from AAC to M4A actually reduce my audio quality?
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If AAC is lossy (MP3, AAC) and M4A is lossless (WAV, FLAC), the M4A is no better than the AAC — you cannot recover information already discarded by the lossy AAC codec. If AAC is lossless and M4A is lossy, expect the M4A encoder to recompress; at 192 kbps the loss is imperceptible to most ears.
Can I batch-convert hundreds of AAC files into M4A?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Can I normalize loudness in the AAC to M4A step?
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Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished M4A through a Normalize tool on this site.
Will the M4A play on my car stereo / iPod / Sonos / Bluetooth speaker?
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MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports. M4A keeps rich iTunes-style metadata, chapters and artwork intact, and is the native audio format across every Apple device. M4A hides two very different things behind one extension — lossy AAC and lossless ALAC — and non-Apple hardware support is inconsistent.
Is my AAC file private during conversion?
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Yes. Uploaded AAC files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted M4A are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.
How long does converting a 1-hour AAC to M4A take?
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It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame.
Why is the M4A file louder or quieter than the AAC source?
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The converter does not change the level: it has no gain or normalize setting. If you hear a difference, your player or media library is probably applying ReplayGain or its own volume levelling on playback; switch that off to hear the M4A as it is.
