Convert AAC to MP3
Convert an AAC file to MP3 for a device that will not read AAC. Be clear about what this is: AAC is the newer and better codec, so this is a downgrade taken deliberately in exchange for compatibility. It is the right trade when the destination is a car stereo, an old player or a piece of software with a fixed list of formats, and the wrong one otherwise.
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Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- For hardware that predates AAC support
- Encoded at a high variable-bitrate setting
- Honest about being a quality trade
- No watermark and no sign-up
How to use AAC to MP3
- 1
Add the AAC
Drop the file in or choose it from your computer. Files up to 50 MB, no account needed.
- 2
Convert
The AAC is decoded and re-encoded to MP3 at a high variable-bitrate setting.
- 3
Use it where AAC was refused
The MP3 plays on hardware and in software that has no AAC decoder.
A conversion that goes backwards, on purpose
Most conversions on this site move a file toward something better supported and at least as capable. This one does not. AAC — Advanced Audio Coding — was standardized in 1997 as the successor to MP3, and it does the same job better, especially at lower bitrates where MP3 starts to sound obviously compressed.
Converting AAC to MP3 gives you a file that is technically worse. The reason to do it anyway is that MP3 is supported by every piece of audio hardware and software made in the last thirty years, and AAC is not.
That is a real trade rather than a mistake, and it is worth making deliberately. A file that will not play on the device you need it on has no quality at all.
Where AAC support actually runs out
Car head units are the commonest place. Units built through the 2000s and into the 2010s frequently list MP3 and WMA on the box and nothing else, and an AAC file on a USB stick is either invisible in the folder listing or skipped without explanation.
After that: older portable players, a surprising number of Bluetooth speakers with onboard storage, cheap in-car adapters, some digital voice recorders, and software with a hard-coded list of accepted formats — transcription services, older audio editors, upload forms.
How it works
The AAC is decoded to samples and those samples are encoded to MP3 at a high variable-bitrate setting, which spends more data on complicated passages and less on simple ones.
Because AAC is itself lossy, this is a second generation of loss. The first encoder discarded what it judged inaudible; the second now works from that already-reduced audio and makes its own judgments, which do not line up with the first encoder's. That mismatch is where the extra damage comes from.
When not to do this
If the destination reads AAC, leave the file alone. If you have the original recording in a lossless form, encode the MP3 from that instead — a first-generation MP3 from a WAV or FLAC is noticeably better than a second-generation one from an AAC, at exactly the same file size.
Convert AAC to MP3 when the AAC is what you have and the device is what it is.
Examples
A file for an old car stereo
Head units from the 2000s often list MP3 and WMA and nothing else. The AAC either does not appear in the folder listing or is skipped silently.
Audio for software with a fixed format list
Transcription services, older editing tools and some upload forms accept MP3 and WAV only, and reject anything else on the extension.
Frequently asked questions
Is MP3 better than AAC?
No, and it is worth saying so on a page whose whole purpose is converting one to the other. AAC was designed as MP3's successor and is measurably better at the same bitrate, particularly below about 128 kbps. The only thing MP3 has over it is age: it is supported by essentially everything ever made, and AAC is not.
So why would I convert?
Because a file that will not play is worth less than a slightly worse file that will. Car head units, older portable players, some Bluetooth devices with onboard storage and a good deal of software have no AAC decoder. Compatibility is a real requirement, not a lesser one, and it is the only reason to make this conversion.
How much quality do I lose?
Some, and more than you would from a lossless source, because this is a second lossy encode. AAC has already discarded what its encoder judged inaudible; the MP3 encoder now works from that reduced version and discards what it judges inaudible, and the two do not agree. For speech this is not audible. For music at a high bitrate it is slight but real.
Is an M4A file the same as an AAC file?
Nearly. M4A is an MP4 container holding an AAC track, which is what iTunes and most Apple software produce. A bare `.aac` file is the raw stream with no container. The audio inside is the same kind of thing, and both convert to MP3 the same way.