AAC is the standard for Apple devices, YouTube, and most streaming services. Same compression family as MP3 but slightly more efficient. The places that still need MP3 are older car stereos, embedded media players, voicemail systems, and cheap MP3-only USB drives. That's the conversion this tool handles.
Either raw .aac files or .m4a files (which are AAC inside an MP4 container). Both decode the same.
Up to 200 MB
Most AAC sources are encoded at 128-256 kbps. Re-encoding to 320 kbps MP3 doesn't add quality. It just keeps every detail of the source. For files going to old hardware, 192 kbps is plenty.
Encoder: libmp3lame · CBR
Tags from the AAC's MP4 container map to ID3v2 on the MP3, so artist/album/title carry over.
Standard MP3 with ID3v2
For the device that won't cooperate
AAC is what Apple, YouTube, and most streaming use, and your phone plays it fine. But older car head units, embedded players, voicemail systems, and bargain-bin USB drives still only understand plain MP3. This converts your AAC files into the one format nothing has ever refused, so they finally play where you need them.
Straight talk on quality
AAC and MP3 are both lossy, so going from one to the other adds a small second generation of compression. At 320 kbps it's below what most people can hear, but it isn't literally zero. If you happen to have the original lossless file, encoding MP3 from that is always cleaner than converting the AAC. If AAC is all you've got, 320 keeps as much as there is to keep.
In your browser
The conversion runs locally with ffmpeg, your files never go to a server, so there's no upload wait and nothing to trust with your music. Title, artist, album, and track number map from the AAC's MP4 metadata straight onto ID3 tags, so the MP3 shows up properly wherever you play it.
Some, yes. Both are lossy and re-encoding adds a generation of compression on top of what the AAC already lost. At 320 kbps the difference is below most listeners' threshold of audibility, but it's not zero. If you have access to a lossless source, encode MP3 from that instead.
At the same bitrate, AAC compresses more efficiently. A 256 kbps AAC sounds roughly equivalent to a 320 kbps MP3. AAC also handles complex frequencies (cymbals, reverb tails) better. MP3 has wider compatibility. Every device built since the late 90s plays MP3, while older devices may not handle AAC.
Yes. AAC files use MP4 metadata atoms; MP3 uses ID3 tags. ffmpeg maps between them automatically. Title, artist, album, year, genre, track number all transfer.
Choose a file or drag it here
Supports WAV · FLAC · MP3 · M4A · AIFF