Upload a FLAC file and get a M4A back. No signup, no watermark, no limit on how many.
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.
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.
This conversion exists because of a wall rather than a quality question: Apple's software will not import a FLAC. Not iTunes, not Apple Music, not the Music app on a phone — the file is simply not on the list, and no preference changes that. Encoding the audio as AAC and wrapping it in an MP4 container produces the .m4a that Apple treats as a first-class citizen, and your artist, album and title come across with it, so a tagged FLAC library arrives as a tagged M4A library.
Keep the FLAC. This is a one-way copy made for a device, and the moment you want a different bitrate — or the phone dies and you start again — the FLAC is what you go back to. Two things worth knowing about the Apple end of it. If you want lossless on Apple hardware, the format is ALAC rather than AAC, and this page does not write it. And if the destination is an Apple Music library that syncs, converting first is the right move regardless, because there is no route that takes the FLAC directly.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
Yes, though this is the most favourable version of that trade available here. AAC gets more out of each kilobit than any of the other three codecs, and from a lossless source at 192 kbps the result is one most listeners cannot separate from the FLAC on a phone, in a car or on ordinary headphones. Best is a fixed 192 kbps rather than a variable setting; if the album is one you care about more than usual, take 256 or 320 from the list instead.
About a fifth of the FLAC, plus a few kilobytes for the container. A 30 MB album track lands near 6 MB, and because the bitrate is fixed the whole library scales predictably — useful when you are deciding how much of it will fit on a phone. Cover art is the one thing that does not come across, so if you add it back afterwards, budget for the image, which is often larger than the container overhead.
Yes — M4A is one of the formats this converter writes, so the reverse page exists at /m4a-to-flac/. Be clear about what comes back, though: the FLAC you get is a faithful copy of the M4A, not of the original. The loss happened on the way out, and returning to a lossless format stops further loss rather than undoing it. Keep the original FLAC if you still have it.
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.