MP3 to AAC Converter
When a player, a broadcast tool or an upload form names AAC as its format, convert your MP3s here and get .aac files at the bitrate you choose.
Audio Converter
or drop MP3, WAV, M4A … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
Constant bitrate (CBR) gives a predictable size and works on every player. Variable bitrate (VBR) spends bits where the music needs them and is usually smaller at the same quality.
Keep the source rate unless a device asks for one. 44.1 kHz is CD standard, 48 kHz is video standard, 8 kHz is used by phone systems and AMR.
Mono halves the size of lossless files and is fine for voice recordings.
16-bit is CD quality. 24-bit keeps headroom for editing and mastering; converting a 16-bit source up does not add detail.
Optional. Seconds (e.g. 75) or minutes:seconds (1:15). Leave empty to start at the beginning.
Optional. Same format as the start time. Leave empty to keep everything up to the end.
How to use this tool
- 1
Upload the MP3s
Add up to 20 MP3 files, each up to 95 MB. Albums, podcast episodes and voice recordings all work.
- 2
Match the bitrate
Bitrate starts at 192 kbps with Bitrate mode on Constant (CBR), which older hardware handles best. Set it to the MP3's own bitrate, or lower for speech.
- 3
Convert to AAC
Press Convert to AAC and download the .aac files. Test one on the target device before copying a whole library.
How do I convert MP3 to AAC?
Upload the MP3s, leave Convert to on AAC and press Convert to AAC. You get raw .aac files at 192 kbps constant bitrate. If an app or phone expects AAC inside an .m4a file, choose M4A instead.
When a device or form asks for AAC instead of MP3
AAC was standardized by MPEG in 1997, as part of MPEG-2, with the explicit goal of replacing MP3 by delivering similar quality at lower bitrates. It became the format of the iTunes Store and of the audio track in most MP4 video, and nearly every phone, browser and recent car stereo decodes it.
Converting an MP3 to AAC does not make it sound better: the MP3 encoder already removed detail, and AAC can only encode what is left. People convert for practical reasons instead. A spec sheet, playout system or submission form lists AAC and not MP3. A music library is being made consistent with AAC purchases. Or storage is tight and a lower-bitrate AAC copy is good enough for spoken word.
MP3 to AAC or MP3 to M4A: which file to make
Raw AAC (ADTS)
AAC frames written one after another, each with a small header, and no container around them.
- Streams and joins cleanly
- Matches hardware and broadcast tools that list .aac
- No seek index, so some players misjudge the length
- Little room for tags or cover art
AAC in an MPEG-4 file
The same AAC audio wrapped in an MP4 container with an index and a metadata section.
- Exact duration and fast seeking
- Titles, artist, album and artwork
- What the Music app on iPhone and Mac uses
- Pick M4A under Convert to
How big the AAC file will be
1.44 MBper minute of AAC at 192 kbps, exactly the same as a 192 kbps MP3
So the AAC comes out smaller only if you choose a lower bitrate than the MP3 has. Going higher is wasted space: a 128 kbps MP3 converted at 320 kbps is two and a half times larger and sounds the same. A sensible rule is to match the MP3's bitrate for music and step down to 96 or 128 kbps for speech.
Licensing is no longer part of the decision either, because the last MP3 patents expired in 2017. What matters is what the destination accepts. For an Apple library with proper tags, MP3 to M4A is usually the better pick; to undo a conversion later, AAC to MP3 takes raw .aac files back.
MP3 and AAC: format facts
MP3
MP3 audio
MP3 (MPEG-1 Audio Layer III) is a lossy audio format developed largely at the Fraunhofer Institute and standardised by MPEG in 1993. It removes sounds the ear is unlikely to notice, shrinking music to about a tenth of CD size at 128–320 kbps. All patents have expired, and every phone, car stereo, browser and media player supports it. Quality loss is audible at low bitrates and accumulates with re-encoding.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 1993 · Fraunhofer IIS / MPEG
AAC
Advanced Audio Coding
AAC is a lossy audio codec standardised by MPEG in 1997 as the successor to MP3. It delivers better quality than MP3 at the same bitrate and is the default audio in MP4 video, YouTube, Apple Music and most streaming services. Raw .aac files contain only the stream, while M4A and MP4 files wrap it in a container. Nearly every modern device plays AAC.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 1997 · Moving Picture Experts Group (MPEG)
MP3 is turned into AAC when a player, playout system or upload form specifies AAC, or when a library is being brought in line with AAC purchases; the conversion changes compatibility and file size, never the quality the MP3 already set.
MP3 to AAC questions
Will my car stereo play the .aac files?
If its manual lists AAC, usually yes, but check whether it means .aac or .m4a files; some head units only read one of them from a USB stick. Test a single file first. If neither works, MP3 at its original bitrate remains the safest choice for car audio.
Is AAC better than MP3 at the same bitrate?
When both are encoded from the same lossless source, AAC generally sounds cleaner at 128 kbps and below, which is a large part of why it replaced MP3 in many services. From an MP3 source that advantage cannot show up, because the encoder starts from audio that has already lost detail.
What AAC bitrate suits an audiobook or podcast MP3?
Speech holds up well at low rates: 64 kbps in mono or 96 kbps in stereo keeps voices clear. Set Channels to Mono when there is a single narrator. At 64 kbps an hour of audio comes to about 29 MB.
Are AAC-LC and HE-AAC the same thing?
They are profiles of the same family. AAC-LC (Low Complexity) is the everyday profile for music at mid and high bitrates and plays on practically everything. HE-AAC adds tricks for very low bitrates, such as internet radio at 48 kbps, and older devices may not decode it.
Do the ID3 tags from my MP3 survive in a raw .aac file?
Only partly. Raw .aac has no proper tag structure of its own, so many players show just the file name even with Keep tags and cover art switched on. If titles and artwork matter, convert to M4A instead, which stores them in the MP4 container.
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