Upload a AIFF file and get a M4A back. No signup, no watermark, no limit on how many.
AIFF is Apple's uncompressed PCM format — WAV's opposite number, same audio, different byte order and a container that handles tags rather better.
Where you run into it: Logic and Pro Tools sessions, Mac recordings, older Apple software that wrote it by default.
What it costs you: As big as WAV, and outside the Mac world rather less widely accepted.
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.
Both ends of this conversion are formats Apple reads natively, which makes it unusual on this site: nothing about compatibility changes. Your Mac played the AIFF, your Mac plays the M4A, the Music app takes either. What changes is the size, by a factor of about twelve, and that is the entire point. An AIFF is uncompressed, so a folder of Logic bounces fills a disk at roughly 10 MB a minute; the same audio as AAC in an MP4 container is a manageable library instead of an archive.
This is the conversion for getting your own recordings off the Mac and onto something you carry. Voice memos, interview tapes, rehearsal recordings and Logic bounces all tend to arrive as AIFF and all tend to be far larger than they need to be for listening. Keep the AIFF for anything you might edit again; the M4A is the listening copy. If you would rather not give up any audio at all, FLAC halves the file and stays exact — it just will not go into the Music app.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
Yes, and how much depends on what your AIFF is. An ordinary AIFF or an AIFF-C marked sowt is uncompressed, so AAC at Best — a flat 192 kbps — is the only thing discarding anything, and from that starting point it is a result most people cannot separate from the original. An AIFF-C holding IMA4 or µ-law was already lossy, and then this is a second encode. High sample rates and surround both survive intact, which is not true of the MP3 route.
About a twelfth of the AIFF, plus a few kilobytes of container. A four-minute stereo bounce goes from roughly 40 MB to roughly 5.5 MB, and because Best is a fixed rate rather than a variable one, a whole folder scales predictably — which is what makes this the practical way to decide how much of a session archive will fit on a phone.
Not here. AIFF can be read but not written by this converter — ffmpeg decodes it happily, and encoding back to it would mean a format almost nothing plays. If you need the original AIFF, keep it rather than recreating 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.