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Convert a .aac recording into an MP3 that any player, editor or upload form accepts. The conversion runs in your browser, so the file stays on your device.
Your media is processed in your browser and is not uploaded to our servers for conversion. Page assets (including the converter engine) still load over the network.
Select or drop a video or audio file
MP4, MOV, WebM, MKV, M4A, WAV, FLAC, OGG and more. Converted on your device.
Click, tap, or drop a fileChoose the .aac file
Drop or select the file from your recorder or Downloads folder.
Pick the bitrate
192 kbps suits music; 128 kbps is plenty for recorded speech.
Convert
The AAC audio is decoded and saved as MP3 on your device.
Download
Check it in the player, then download.
AAC is the codec inside most MP4, M4A and iPhone audio, but a bare .aac file (raw ADTS stream) usually comes from Android voice and call recorders, some dashcams and radio or streaming recorders. Many desktop players, older car stereos and upload forms don't recognise the .aac extension even though they play M4A.
If your file ends in .m4a instead, the M4A to MP3 page covers iPhone voice memos and Apple audio.
FFmpeg in WebAssembly decodes the AAC stream and encodes it with the LAME MP3 encoder. Raw .aac files have no length stored in them, so the duration may only show once the MP3 is ready.
AAC to MP3 is a lossy re-encode. At 128 kbps or above speech sounds unchanged; for music choose 192 kbps. If an app accepts M4A, choosing M4A with Original quality wraps the AAC without re-encoding.
Handles .aac files that many players reject.
Choose M4A, Original to rewrap the audio with no quality change.
128 kbps for speech, 192 or 320 kbps for music.
Recordings are converted on your device.
No. The conversion runs in your browser with a WebAssembly build of FFmpeg. Your file is read from your device and the result is saved back to it; nothing is sent to our servers.
M4A is an AAC stream inside an MP4 container. A .aac file is the stream on its own. Both use the same codec and both open here.
Raw AAC files don't store their length. Conversion still works; the time is known once the MP3 is finished.
Slightly, as it is a re-encode. At 192 kbps you won't hear a difference. To avoid any change, convert to M4A with Original quality instead.
192 kbps (High) sounds transparent for most music and is the default. 128 kbps is plenty for speech such as lectures and voice notes. 320 kbps only helps if the source audio is already high quality; it cannot add detail that isn't there.
Files up to 4 GB and 4 hours long on a computer, or 2 GB and 2 hours on a phone. The video is read in pieces rather than loaded into memory, so large recordings work; only the audio file being written has to fit in memory.
Related: M4A to MP3 · AMR to MP3 · Audio Converter · Audio Cutter · All tools