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MP3AAC

Convert MP3 to AAC

This free MP3 to AAC converter changes your MPEG-1 Audio Layer III (.mp3) file into a Advanced Audio Coding (.aac) file, right in your browser. There is nothing to install, no account to create, and no limit on how many files you convert.

100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

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The conversion runs on your own device using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is never uploaded to a server. AAC is best for streaming and mobile devices, which is the usual reason to convert from MP3.

Why convert MP3 to AAC?

  • Note: AAC has narrower support than MP3 - convert only when a specific app or workflow needs it.
  • At a sensible bitrate, AAC stays close in size to MP3 while changing the codec.
  • Pick AAC when you need a file made for streaming and mobile devices.

MP3 vs AAC

PropertyMP3AAC
Full nameMPEG-1 Audio Layer IIIAdvanced Audio Coding
ContainerMP3ADTS
Typical codecMP3AAC
CompatibilityUniversalWide
LosslessNoNo
Best forUniversal music and podcast playbackStreaming and mobile devices

How to convert MP3 to AAC

  1. Add your MP3 file

    Drag and drop your .mp3 file onto the upload area, or click to browse and pick it from your device.

  2. Start the conversion

    Click "Convert to AAC". Everything runs locally with ffmpeg compiled to WebAssembly (ffmpeg.wasm) - your file stays on your device.

  3. Wait a few seconds

    A progress bar shows the conversion. The first run is slightly slower while the engine loads, then it is cached.

  4. Download your AAC file

    When it finishes, download the .aac file straight to your device.

Frequently asked questions

Is this MP3 to AAC converter free?
Yes. It is completely free with no signup, no watermark, and no limit on how many files you convert. It is supported by ads, which keeps the conversion itself free.
Are my files uploaded to a server?
No. The conversion runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is processed in memory on your own device and is never uploaded, stored, or seen by anyone.
Will I lose quality converting MP3 to AAC?
The audio is re-encoded to AAC, which is lossy. At a sensible bitrate the difference is hard to hear, but converting back and forth repeatedly will degrade quality.
Will the file get smaller or larger?
Roughly the same. MP3 and AAC have comparable size profiles at a sensible bitrate.
What is the difference between MP3 and AAC?
MP3 is MPEG-1 Audio Layer III (an MP3 container, typically MP3); AAC is Advanced Audio Coding (an ADTS container, typically AAC). AAC is best for streaming and mobile devices, while MP3 is best for universal music and podcast playback.
How long does the conversion take?
Most files finish in a few seconds to under a minute, depending on length and your device. The first conversion is a little slower while the engine downloads and caches, then later runs start instantly.

Related conversions

M4A → AACMP3 → WAVMP3 → M4AMP3 → OGG

Need more formats or options? Use the full Audio Converter.