About this tool
M4A (AAC) is the native audio format of the Apple ecosystem: iTunes, Apple Music, iMovie, and Final Cut all prefer it, and an iPhone ringtone is simply an M4A renamed to .m4r. This converter re-encodes your MP3 to AAC in your browser at the bitrate you choose.
About the formats: MP3 is the universal lossy audio format. Practically every device, car stereo, and app made in the last 25 years plays it, and at 192-320 kbps it is indistinguishable from the original for most listeners. M4A is AAC audio inside an MP4 container, Apple's default for Voice Memos, iTunes purchases, and many recording apps. Quality is excellent, but plenty of players and web forms only accept MP3.
Everything happens inside your browser. Your file is never uploaded to a server: the conversion runs on your own device using WebAssembly, and the result is downloaded straight from memory. Close the tab and nothing is left behind.
How to use it
- Drop your MP3 files into the box above, or click to browse. Nothing is uploaded.
- Adjust the options if you want; the defaults suit most files.
- Click Convert to M4A and wait a moment.
- Download the results individually or all at once as a ZIP.
Frequently asked questions
How do I make an iPhone ringtone?
Convert the MP3 to M4A, rename the file extension from .m4a to .m4r, and add it through iTunes or the Finder. Ringtones must be 40 seconds or shorter, so trim the audio first if needed.
Is AAC better than MP3?
At the same bitrate, yes: AAC is a newer codec and sounds slightly cleaner at 128 kbps. Converting from MP3 cannot restore detail already lost, though.
Is this really free?
Yes. The site is supported by ads, and there are no limits on how many files you convert.
Are my files uploaded anywhere?
No. The converter runs entirely in your browser. Files stay on your device, which also makes it faster than upload-based converters for anything larger than a few megabytes.
Is there a file size limit?
The only limit is your device's memory. Images and audio of any normal size are fine; for video, files under about 500 MB work well on most laptops and phones.
Which browsers are supported?
Current versions of Chrome, Edge, Firefox, and Safari on desktop and mobile. Very old browsers without WebAssembly support will not work.