Convert MP3 to AAC, as a .aac stream or an .m4a file
This MP3 to AAC converter re-encodes MP3 files with AAC, the codec behind the iTunes Store, YouTube, DAB+ digital radio and the audio track of most MP4 videos. You can save the result as a raw .aac stream or as an .m4a — the same AAC audio inside an MP4 file — at any bitrate from 64 to 320 kbps. Conversion happens inside your browser, so your music stays on your device.
People usually make this switch for one of three reasons: an app, device or upload form that asks for AAC specifically; a library being standardised on AAC for Apple devices; or smaller files, since AAC tends to sound better than MP3 at modest bitrates. Both formats are lossy, though, so turning an MP3 into AAC is a second round of compression — choose a bitrate at least as high as the MP3’s, which the file list shows for every file.
How to use the MP3 to AAC Converter
- Drop one or more MP3 files on the upload area.
- Under Convert to, pick AAC (.aac) for a raw ADTS stream or M4A (AAC) for an MP4 file that iPhones, iTunes and the Music app import directly.
- Choose a Bitrate. Match or exceed the MP3’s bitrate shown under each file; 192 kbps is a good default, 256 kbps matches iTunes Store downloads.
- Press Convert to AAC (or M4A) and follow the progress bar.
- Compare the two players, then download the files one by one or as a ZIP.
MP3 to AAC Converter features
Two AAC flavours
Raw ADTS .aac for players and tools that want the bare stream, or .m4a in an MP4 container with an index for fast seeking and an exact duration.
AAC-LC encoding
Low Complexity AAC, the profile every AAC decoder supports. Your browser’s encoder does the work; a libavcodec AAC encoder takes over for bitrates the browser refuses.
Tags and artwork kept
ID3v2 tags become MP4 metadata atoms in .m4a, or an ID3 tag in front of the .aac stream, cover art included.
Lossless .m4a ↔ .aac switch
Already have AAC? Drop an .m4a and choose .aac (or the reverse) and the audio is copied across untouched.
Batch and ZIP
Convert an album at once and download it as one archive.
.aac or .m4a — which should you pick?
The audio inside is identical, so you can switch later without any loss: the audio converter rewraps AAC between the two in seconds. If an app simply says “AAC file”, .m4a is usually the safer bet.
| .aac (ADTS) | .m4a (MP4) | |
|---|---|---|
| What it is | A bare AAC stream; every frame carries a small header | AAC audio in an MP4 container with an index |
| Seeking and duration | Estimated by scanning frames; can be approximate | Exact, with instant seeking |
| Tags and cover art | ID3 tag at the start, read by many but not all players | iTunes-style metadata atoms, read wherever AAC plays |
| Best for | Tools, broadcast workflows and apps that ask for “.aac” | iPhone, iTunes and Music, Android, sharing |
MP3 vs AAC at the same bitrate
AAC was designed as MP3’s successor and standardised in MPEG-2 (1997) and MPEG-4 (1999). It uses a more flexible transform, handles sharp transients better and codes stereo more efficiently, so at 96–128 kbps it generally sounds cleaner than MP3. At 256–320 kbps both are close to transparent for most listeners.
That advantage only fully applies when AAC encodes from a lossless source. From an MP3, the AAC encoder faithfully preserves the MP3’s artefacts along with the music and adds a little of its own. The rule of thumb: never go below the MP3’s bitrate, and expect the AAC to sound like the MP3, not better.
Tips for Apple devices
- Choose M4A for anything going into the Music app or iTunes for Windows; it shows the title, artist and cover art straight away.
- An iPhone ringtone is an AAC .m4a renamed to .m4r and kept to 40 seconds or less. Trim the song with the Audio Cutter, convert the clip here to M4A and rename the file — MP3 to M4A walks through the steps.
- AAC at 256 kbps is the format of iTunes Store purchases, so it is a natural ceiling for music you add yourself.
MP3 to AAC Converter FAQ
How do I convert MP3 to AAC?
Drop the MP3 here, pick AAC (.aac) or M4A (AAC), choose a bitrate and press Convert. The AAC file downloads when it’s done.
Is AAC better than MP3?
At the same bitrate AAC usually sounds better, especially at 128 kbps and below. Converting an existing MP3 won’t make it sound better, though — it can only stay as good as the MP3.
What bitrate should I use for MP3 to AAC?
At least the MP3’s own bitrate, which is shown for each file. 192 kbps suits most music; 256 kbps matches iTunes Store files.
What is the difference between AAC and M4A?
AAC is the codec; M4A is an MP4 file that contains AAC audio. A .aac file is the raw AAC stream without the MP4 wrapper.
Will my iPhone play the converted file?
Yes — .m4a files play natively on iPhone, iPad and Mac and can be added to the Music app. Raw .aac files also play, but show less metadata.
Are my files uploaded?
No. The MP3 is decoded and the AAC encoded inside your browser tab; only the encoder code is downloaded.