Upload a M4A file and get a FLAC back. No signup, no watermark, no limit on how many.
M4A is an MPEG-4 container holding AAC audio — the same codec as a bare .aac file, wrapped so that players, tags and cover art all behave.
Where you run into it: iTunes and Apple Music purchases, voice memos, Zoom and Teams recordings, most phone-recorded audio.
What it costs you: Outside Apple's ecosystem support is good but not universal, and a few older tools still refuse the extension on sight.
FLAC compresses losslessly: it typically halves a WAV and gives back bit-for-bit the same audio when decoded. It is free, open, and widely supported outside Apple's world.
Where you run into it: Archived rips, Bandcamp and Qobuz downloads, anyone who keeps a music library they intend to still have in ten years.
What it costs you: Half of enormous is still large, and some hardware — car head units especially — will not touch it.
This is the pair in the group where the answer depends entirely on what is inside the container, and the good case is very good indeed. If your .m4a holds Apple Lossless, nothing was ever discarded and this conversion is exact — the samples come across unchanged, 24-bit ones included, because FLAC keeps the full depth. If it holds AAC, which is the more common case, the FLAC is a faithful record of a lossy file at several times the size. Get Info in Music or iTunes names which of the two you have outright.
When the file is ALAC, the reason to do this is that Apple Lossless is a good format in a bad neighbourhood: outside Apple's own software and hardware, support for it is patchy, while FLAC is read by practically everything that plays music — Android, Plex, Sonos, Roon, car units, VLC on anything. Converting an ALAC library to FLAC gives up nothing and gains the rest of the world. If you are unsure which you have, ffprobe reports the codec as alac or aac; the extension will not tell you, because .m4a names only the container.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
For Apple Lossless, none at all: ALAC and FLAC are both lossless, so the audio survives bit for bit and so does the depth — a 24-bit ALAC becomes a 24-bit FLAC. For AAC, nothing further is lost and nothing is recovered; you are preserving what the first encoder left behind. The distinction matters more here than anywhere else in this group, because it separates a genuine archival step from an expensive copy.
It turns on the same question. From Apple Lossless, roughly the same or a little smaller — both formats are doing the same job, and FLAC is generally the slightly more efficient of the two. From AAC, five to eight times larger, because a lossless format has to store every sample of whatever it is handed.
Yes — FLAC is one of the formats this converter writes, so the reverse page exists at /flac-to-m4a/. The trip out is exact, because FLAC discards nothing — it is the return to M4A that re-encodes. A round trip therefore costs one more generation rather than two, and the FLAC in the middle was never an improvement on the M4A you started with.
The file is uploaded to do the conversion — nothing here runs in your browser — and both your upload and the converted result are deleted the moment the file is sent back. Nothing is stored and nothing is logged beyond the request itself.