AAC to MP3
Convert raw AAC audio files to widely playable MP3. Nothing is uploaded.
Drop AAC files here
Converted on your device. Files are never uploaded.
Up to 20 files at a time.
AAC audio saved as a raw stream, with the .aac extension, doesn’t open in every player or editor, even though the audio inside is common. MP3 is accepted almost everywhere. FormatJet decodes the AAC and encodes the MP3 in your browser, so your recordings stay on your device.
About the formats
AACAAC audio
An .aac file is a raw stream of AAC audio, the codec inside most M4A and MP4 files. It sounds better than MP3 at the same size, but fewer players open bare AAC files.
MP3MP3 audio
MP3 is the most widely supported audio format. Its lossy compression makes music about a tenth of the size of a CD, and every phone, car and player can play it.
Converted with Mediabunny, Browser audio decoder (WebCodecs), LAME MP3 encoder, Media engine (FFmpeg).
Questions
What is a .aac file?
A raw AAC stream, the same kind of audio an M4A holds but without the MP4 container around it. Some apps and devices save audio this way, and plenty of players won’t open it on its own.
Does AAC to MP3 make the audio worse?
It can’t improve it. Both formats are lossy, so the MP3 is a second encode of sound that was already compressed; a higher bitrate in Options limits what’s lost, starting from the default of 192 kbps.
Why does my browser matter?
FormatJet hands the AAC to your browser’s built-in decoder through WebCodecs, so it needs a recent Chrome, Edge, Firefox or Safari. If yours can’t decode the stream, you get a message rather than an MP3.
Can I convert several AAC files together?
Yes, up to 20 at once. Results keep the original file names with .mp3 at the end and download singly or as a ZIP.
AAC to MP3 with the API
The conversion API opens later this year.
curl https://api.formatjet.com/v1/convert?to=mp3 \
-H "Authorization: Bearer fj_test_…" \
-F file=@input.aac -o output.mp3