Convert AAC audio, from raw .aac recordings and radio streams to M4A files, into MP3 that plays on older players, car stereos and any app. Convert a whole batch at once on your own device, with no upload.
MP3 quality
Tip: AAC sounds better than MP3 at the same bitrate, so pick an MP3 bitrate a step higher than the source: 128 kbps AAC → 192 kbps MP3, 256 kbps AAC → 320 kbps MP3.
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How to use the AAC to MP3
Add your AAC files: drop .aac or .m4a files on the box, or click Choose AAC files.
Pick the MP3 bitrate: one step above the AAC bitrate keeps the quality, for example 192 kbps for 128 kbps AAC.
Adjust channels, sample rate or normalization if you need to; the defaults keep the original.
Press Convert to MP3. Each file shows progress and its new size.
Download each MP3, or press Download all (ZIP).
AAC versus MP3 at common bitrates
AAC (Advanced Audio Coding) was designed as the successor to MP3 and is more efficient, so an MP3 needs a somewhat higher bitrate to sound equally good. Use this as a guide when choosing the MP3 bitrate:
AAC source
Typical origin
Suggested MP3
MP3 size per minute
HE-AAC 32 to 64 kbps
Internet radio, podcasts, voice recorders
128 kbps (mono for speech)
0.96 MB
AAC-LC 96 to 128 kbps
Phone recordings, video soundtracks
192 kbps
1.44 MB
AAC-LC 160 to 192 kbps
Streaming, screen recordings
256 kbps
1.92 MB
AAC-LC 256 kbps
iTunes and Apple Music purchases (DRM-free)
320 kbps
2.4 MB
The MP3 size follows bitrate ÷ 8 × seconds: 192,000 ÷ 8 = 24,000 bytes per second, or 1.44 MB per minute.
File types that contain AAC
.aac: raw AAC in ADTS frames, with no tags. Each frame starts with a small header holding the profile, sample rate and channel count, which the tool reads and shows.
.m4a / .m4b: MPEG-4 audio files and audiobooks. Tags such as title, artist and cover art are copied into the MP3.
.mp4 / .3gp: video files. The AAC soundtrack is converted and the picture is ignored.
.m4p: DRM-protected iTunes purchases from before 2009 cannot be converted by any browser tool.
HE-AAC and sample rates
HE-AAC (also called AAC+) stores the audio at half the sample rate and rebuilds the high frequencies with Spectral Band Replication, so a file may announce 22.05 or 24 kHz in its header while decoding to 44.1 or 48 kHz. The tool shows the decoded rate and, with Keep original, the MP3 uses that same rate.
Frequently asked questions
How do I convert AAC to MP3?
Add your .aac or .m4a files here, choose an MP3 bitrate and press Convert to MP3. Your browser decodes the AAC audio and the page encodes it to MP3, so the files never leave your device. Download them one by one or as a ZIP.
What is the difference between AAC and M4A?
AAC is the audio codec. A .aac file is raw AAC in ADTS frames, often from radio streams, recorders and video tools. A .m4a file is an MPEG-4 container that usually holds AAC audio plus tags and cover art. This tool converts both.
Is AAC better than MP3?
At the same bitrate AAC usually sounds better, especially at 128 kbps and below. MP3 is still more compatible with older MP3 players, some car stereos, DJ software and websites, which is why people convert to it.
Which MP3 bitrate should I choose?
Choose an MP3 bitrate a little higher than the AAC source to avoid an audible drop: 192 kbps for 128 kbps AAC, 256 to 320 kbps for 256 kbps AAC, and 128 kbps mono for speech.
Can I convert HE-AAC (AAC+) files?
Yes, as long as your browser decodes them, which current Chrome, Edge, Safari and Firefox do on most systems. HE-AAC files are decoded to their full output sample rate, then encoded to MP3.
Why can my AAC file not be converted?
Protected iTunes files (.m4p) cannot be decoded. Some Linux browsers ship without an AAC decoder, and Apple Lossless (ALAC) files in .m4a only decode in Safari. Damaged or truncated files can also fail.
Are my files uploaded?
No. The conversion uses your browser's Web Audio API and the LAME MP3 encoder in JavaScript, so your audio is processed locally.