Is M4A better quality than MP3?

At the same bitrate AAC usually sounds a little better — but converting an MP3 can't add back what it already lost.

Why can't I convert to M4A in Firefox?

Firefox has no AAC encoder yet. Chrome, Edge and Safari do.

Can I convert many MP3s to M4A at once?

Yes, and download them together as a .zip.

MP3 to M4A Converter

Convert MP3 files to M4A in your browser — nothing is uploaded.

MP3, WAV, FLAC, M4A, M4B, MP4, AAC, OGA or WEBA, one or many. Drop them here or paste with ⌘V / Ctrl+V. Choose what each becomes on its row.

Runs on your device. Files are read and converted in your browser and aren't uploaded.

MP3

Lossy
Plays everywhere
Small files

The audio format almost everything plays. MP3 makes small files by leaving out detail most ears won't miss, which makes it the safe choice for music, podcasts and voice notes you want to share, upload or keep on a phone.

MP3 Converter — convert MP3 files to any format

M4A

Lossy
Apple's format
Keeps chapters

AAC audio in an MP4 container — the format of iTunes and Apple Music purchases, iPhone voice memos and many recorders. It sounds a little better than an MP3 of the same size, and plays on Apple devices, Android, Windows and in browsers.

M4A Converter — convert M4A files to any format

Learn more about converting MP3 to M4A

When you'd do this

You want your MP3 in AAC: for an Apple workflow, an app or device that prefers M4A, or to keep everything in one format with your iTunes purchases.

What to expect

A 4-minute MP3 at 192 kbps is about 5.5 MB; the M4A at the default 192 kbps is about 5.5 MB — about the same size.

Recommended settings

Match the MP3's bitrate (192 kbps by default). Going higher makes the file bigger without bringing back anything the MP3 lost.

Where it plays

iPhone, iPad, Mac (Music, QuickTime), Android, Windows and every modern browser.

Good to know

Firefox can't make M4A files yet: use Chrome, Edge or Safari.
The sound is encoded a second time, so it can't sound better than the MP3.
Chrome's AAC encoder takes only 44.1 and 48 kHz; other rates are resampled, and the row says so.

How to do it

Choose your MP3 files, or drop them on the page — as many as you like.
Each is set to M4A. Change one on its own row if you like, and the AAC bitrate and the channels in Settings.
Convert all, then download each M4A, or all of them in one .zip.

Questions

Is M4A better quality than MP3?: At the same bitrate AAC usually sounds a little better — but converting an MP3 can't add back what it already lost.
Why can't I convert to M4A in Firefox?: Firefox has no AAC encoder yet. Chrome, Edge and Safari do.
Can I convert many MP3s to M4A at once?: Yes, and download them together as a .zip.