AnyFormat

00 MP3 → M4A

MP3 to M4A

Better codec, though a second generation on an MP3 source.

Drop files or a folder here

or choose from your device · paste with ⌘V / Ctrl+V

.mp3

03Options 5

Right for speech, wrong for music. At a fixed quality the file size does not change — but mono tolerates a much lower quality than stereo, so combine the two to actually shrink the file.

Leave at 0 for the whole file.

0 means run to the end.

  • No upload The conversion runs in this tab. Your file never travels — not to us, and not to the advertising.
  • No sign-up, no email, no daily cap There is no account system to sign up to.
  • No size limit we invented Only your device's memory — about ~2 GB on a desktop browser, ~400 MB on a phone.
  • Turn your Wi-Fi off and convert anyway The conversion needs nothing but this page. Ads will not load without a connection; your file will still convert. That is the whole claim, and it takes five seconds to check.

Converts MP3 to M4A — AAC audio in an MP4 container. Sensible when a device or application specifically wants M4A; less so as a general upgrade, for the reason below.

A better codec cannot undo the first encode

AAC genuinely is more efficient than MP3. But the MP3 has already discarded detail permanently, and encoding what remains into AAC adds a second generation of loss on top.

The result is not better than the MP3. At High quality it is not audibly worse either, and it is what some devices want. That is the honest case for doing it.

If you have the original lossless source, encode that to M4A instead — one generation rather than two.

Where M4A is required

Apple's ecosystem prefers it: iTunes, Apple Music libraries, and iPhone ringtones (which are M4A with the extension changed to .m4r). Some podcast platforms and some hardware also want AAC specifically.

Choose a bitrate at or above the source

Every re-encode discards more, and the encoder cannot see what the first one already threw away — it only sees the decoded result and treats those artefacts as signal worth preserving. Encoding a 128 kbit/s MP3 to 128 kbit/s AAC therefore sounds worse than the MP3 did, not better, despite AAC being the stronger codec. Matching or slightly exceeding the source bitrate keeps the damage to one generation. If the file is going somewhere that only needs to play it, and not into an edit, the honest answer is usually to leave it as an MP3.

Other names for this

Also searched as “mp3 to aac”, “mp3 to m4a converter”.

Questions

Is M4A better than MP3?
The codec is, at equal bitrate. Converting an existing MP3 to it is not an improvement, because the MP3’s loss is already permanent.
Can I make an iPhone ringtone?
Convert to M4A, trim to under 40 seconds using the trim options, then rename the file to .m4r.
Is my file uploaded?
No. The demuxing, decoding and encoding all happen in this tab using the browser’s own media stack plus a WebAssembly encoder. A recording can be an interview, a lecture, a private call — none of it is transmitted. Turn your Wi-Fi off after the page loads and it still works.
How large a file can I convert?
There is no imposed limit, only your device’s memory — around 2 GB in a desktop browser and 400 MB on a phone, since the file is held in memory while it converts. A two-hour video converts in well under a minute on a laptop.
Can I convert several files at once?
Yes. Drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.