Convert MP3 to M4A
Free online converter for MP3 files. AAC audio in an MP4 container. Nothing to install, no watermark, and every file is deleted automatically.
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Upload a MP3 file to convert it to M4A. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About MP3 and M4A
MP3 .mp3
The format that made digital music portable. Lossy, thirty years old, and still the safest choice when you have no idea what will play the file.
Good for
- Plays on essentially every device ever made
- Small files at listenable quality
- Patents long expired, so support is everywhere
Trade-offs
- Lossy — detail is gone permanently
- Beaten by AAC and Opus at the same bitrate
- No transparency about what was discarded
audio/mpeg
M4A .m4a
An MPEG-4 container holding audio only — usually AAC, sometimes lossless ALAC. The extension tells you the wrapper, not the contents.
Good for
- Rich tagging, including chapters and artwork
- Holds either lossy AAC or lossless ALAC
- The standard for iTunes and Apple Music files
Trade-offs
- The extension alone does not tell you the quality inside
- Support outside Apple platforms is inconsistent
audio/mp4
MP3 and M4A side by side
| MP3 | M4A | |
|---|---|---|
| Compression | Lossy | Container — usually lossy AAC |
| Typically used for | Music, podcasts, anything that must simply play | Apple audio, audiobooks, podcasts |
What changes when you convert MP3 to M4A
This is a re-encode, not a repackage
Some tools can move a stream into a different container untouched when the codecs happen to line up. We do not — every job here is decoded and encoded again, so the conversion takes time in proportion to the length of the file and costs a small amount of quality even where a repackage would have been possible. In exchange the output is predictable: it plays everywhere, rather than inheriting whatever the source happened to contain.
What your M4A will contain
The output is AAC — the same codec a bare .aac file holds, wrapped in an MP4 container so that artwork and tags have somewhere to live.
Re-encoding costs a little quality
Both formats are lossy, so this decodes MP3 and compresses again as M4A. That second pass loses a small amount on top of what was already gone. It is barely audible once, and it accumulates if a file is converted repeatedly — so convert from the original rather than from a previous conversion.
Tags may not survive intact
MP3 stores its metadata as ID3, and M4A uses MP4 atoms. Standard fields such as title, artist and album normally map across. Anything without an equivalent on the other side — unusual custom fields, some ratings and play counts, occasionally embedded artwork — has nowhere to go. Check the tags before deleting the original if your library depends on them.