MP3 to AAC Converter
Convert MP3 to AAC free — no upload, no signup
To convert MP3 to AAC, drop your MP3 audio files into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. Output is AAC in a raw ADTS stream; use MP3 to M4A for music libraries.
Drop audio files here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
Advanced
How to convert MP3 to AAC
Add your MP3 files
Drag and drop MP3 files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Pick a bitrate
192 kbps suits music and 128 kbps or less suits speech. Sample rate and mono/stereo are under Advanced.
Convert and download
Click Convert, then download each AAC file or all of them as one ZIP.
Why convert MP3 to AAC?
Some streaming encoders, broadcast tools and Android apps ask for raw AAC files.
What happens when you convert MP3 to AAC?
The MP3 is decoded and re-encoded as AAC at 160 kbps by default. Converting between lossy formats adds a small generation of loss, so use 192 kbps or higher if quality matters.
How does Fylo convert MP3 to AAC?
Fylo decodes the MP3 audio in the MP3 with ffmpeg compiled to WebAssembly and encodes it with FFmpeg's AAC encoder at 160 kbps, written as a raw ADTS stream. Both formats are lossy, so each conversion discards a little detail — start from the highest-bitrate MP3 you have. A 3-minute song is ≈ 4.3 MB at 192 kbps as MP3 and ≈ 3.6 MB at 160 kbps as AAC. The original sample rate and channel layout are kept unless you change them under Advanced.
What's the difference between MP3 and AAC?
MP3 (MPEG-1 Audio Layer III) was developed largely at Germany's Fraunhofer Institute and standardised in 1993. It removes sounds the ear is unlikely to notice — a technique called perceptual coding — so a 3-minute song takes about 4 MB at 192 kbps instead of about 32 MB as WAV. The last MP3 patents expired in 2017, so it's now free to use.
AAC (Advanced Audio Coding) was standardised in 1997 as part of MPEG-2 and later MPEG-4, designed to replace MP3. It achieves better quality at the same bitrate, especially below 128 kbps. A .aac file is usually a raw ADTS stream; the same audio inside an MP4 container is called M4A.
Learn more: MP3 format guide · AAC format guide
| Property | MP3 | AAC |
|---|---|---|
| Compression | Lossy | Lossy |
| Typical bitrate | 128–320 kbps | 96–256 kbps |
| 3-minute song | ≈ 4.3 MB at 192 kbps | ≈ 3.6 MB at 160 kbps |
| Tags and cover art | Yes (ID3) | Limited in raw .aac (full in M4A) |
| Compatibility | Universal | Very wide: Apple, Android, YouTube, browsers |
| Best for | Music and podcasts on any device | Efficient music and video soundtracks |
| Introduced | 1993 | 1997 |
Frequently asked questions
Is AAC better than MP3?
At the same bitrate AAC usually sounds better, but converting an existing MP3 can't improve it.
What's the difference between AAC and M4A?
M4A puts AAC inside an MP4 container with tags and accurate seeking; .aac is the bare stream.
Is my MP3 file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your MP3 file is read directly from your device and never sent anywhere.
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