Turn M4A files into AAC
This makes an AAC out of the M4A you already have. M4A is the audio file Apple software produces, carrying a track along with its artwork, title and chapters. Your file never leaves your computer.
Need the other direction? Convert AAC to M4A
How to convert M4A to AAC
- 1 Drop your M4A .m4a file onto the page, or click to browse for it.
- 2 Set the quality, or leave the default, which keeps the file small without anything showing.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the AAC, or add more files and do the whole set in one go.
Why convert M4A to AAC
- Better quality than MP3 at any comparable file size.
- Plays everywhere without draining the battery.
- Audio tracks inside MP4 video.
- M4A: some older stereos and players only recognise MP3.
M4A compared with AAC
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | M4A | AAC |
|---|---|---|
| File extension | .m4a | .aac |
| Compression | Lossy or lossless | Lossy |
| Typical file size | Depends on mode | Smaller |
| Introduced | 2001 | 1997 |
| Developed by | Apple / ISO | ISO/IEC MPEG |
Quality and what changes
AAC stores the same content under a different set of rules, so what matters here is compatibility rather than picture quality. Convert once from the best source you have rather than through a chain of intermediate files.
- One AAC limitation to keep in mind: opus sounds better in very small files.
Questions about M4A to AAC
Is my M4A file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your M4A is read straight from your own disk, converted on your machine and handed back as an AAC. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several M4A files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate AAC downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.