Upload a AAC file and get a MP3 back. No signup, no watermark, no limit on how many.
AAC is MP3's designated successor and wins at low bitrates by a clear margin. A bare .aac file is the raw ADTS stream rather than the .m4a container most software expects.
Where you run into it: YouTube and streaming audio tracks, broadcast, anything that came out of a device rather than a music shop.
What it costs you: The naked .aac extension confuses a surprising amount of software, which is the usual reason people convert it.
MP3 is the format that made portable music work, and thirty years on it is still the one every device, car stereo, DAW and browser will open without being asked twice.
Where you run into it: Downloads, podcast feeds, old music libraries, anything a client sends you and expects you to just play.
What it costs you: It throws audio away to get small, and at 320 kbps almost nobody can hear what went. What matters is that the discarded part never comes back.
A bare .aac file is a raw ADTS stream — AAC audio with no container around it, which is why so many players list it and then refuse to seek in it. Converting to MP3 decodes that stream and encodes it again, so it is a second generation, but it also gives the audio a proper frame structure with a duration a player can read. That second part is usually the real fix: files that would not scrub, would not show a length, or played only in VLC behave normally once they are MP3.
Almost every bare .aac arrives from a capture: a radio stream saved by a recorder, a ripped HLS segment, an export from a broadcast tool, or a file a camera or dashcam wrote. That provenance is worth knowing because it tells you there is no better copy to go back to — unlike an .m4a from iTunes, you cannot re-download this one. Convert once, at a generous bitrate, and keep the original .aac even though nothing plays it properly.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
A little, and less than people expect. Raw AAC streams are usually captured at a broadcast or streaming bitrate, and re-encoding at 256 kbps or VBR keeps what is there. The loss that matters on this conversion is not really audible detail — it is that you are encoding a second time, so you should do it once, from the stream you captured, rather than converting an MP3 you already made.
Broadly similar, slightly larger if you match the quality honestly. Raw AAC carries almost no overhead — no container, no tags — so an MP3 of the same audio gains a little from frame headers and any ID3 tags you add. Choosing 128 kbps to save space on an already-lossy capture is where this conversion goes wrong.
Yes — MP3 is one of the formats this converter writes, so the reverse page exists at /mp3-to-aac/. Both formats are lossy, so every leg re-encodes: going out and coming back costs two more generations, and the damage accumulates.
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.