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MP3 to M4A Converter

Turn an MP3 or a WAV into an M4A (AAC) file for Apple Music, an iPhone library or any app that asks for .m4a. Free, no account, and the file is converted in your browser.

Checking whether this browser can write M4A…

Drop your MP3 or WAV here or click to browse

MP3 or WAV, up to 100 MB and 30 minutes.

The file is converted in your browser and is not uploaded.

How to convert MP3 to M4A

One file at a time, all on your device.

  1. 1

    Drop the MP3 or WAV

    Drag the file onto the converter or click to pick it. The page first checks that your browser has an AAC encoder, which is what writes an M4A, and shows the length and the expected size.

  2. 2

    Choose the AAC bitrate

    128 kbps is the default and matches most MP3s. Pick 192 or 256 for music, and turn on mono for a voice recording made with one microphone.

  3. 3

    Download the M4A

    Your browser decodes the audio, encodes AAC and wraps it in an M4A file on your device. Play the preview, then download it under the same name with an .m4a ending.

Why make an M4A

M4A is AAC audio in an MP4 file: Apple's everyday music format.

  • Apple Music and iTunes libraries

    AAC is the format of songs bought on iTunes, so an M4A sits in an Apple library the same way purchased tracks do.

  • Apps that ask for .m4a

    Some editors, upload forms and phone apps list .m4a and not .mp3. Converting gets the file past the picker without changing anything else.

  • Shrinking a WAV

    A WAV from a recorder or an export is uncompressed. As an M4A at 128 kbps the same recording is about an eleventh of the size.

  • One format across devices

    If the rest of your recordings are M4A, from iPhone Voice Memos for example, converting the odd MP3 keeps a folder in one format.

Converting WAV to M4A

The converter takes WAV files too. WAV is uncompressed, so this is where an M4A saves the most space: CD-quality WAV is about 11 times the size of AAC at 128 kbps.

FormatPer minutePer 30 minutes
WAV, 44.1 kHz, 16-bit, stereo10.1 MB302.8 MB
M4A (AAC), 256 kbps1.8 MB54.9 MB
M4A (AAC), 192 kbps1.4 MB41.2 MB
M4A (AAC), 128 kbps938 KB27.5 MB
M4A (AAC), 96 kbps703 KB20.6 MB
AAC sizes follow from the bitrate you pick; real files land within a few percent of it. 1 MB = 1,048,576 bytes.

MP3 to M4A does not improve the sound

MP3 and AAC are both lossy. Converting one into the other decodes the MP3 and compresses it again, so the M4A can only keep what the MP3 already had, and Apple's own guide says you might notice a reduction in sound quality when converting between compressed formats.

To keep that loss small, pick an AAC bitrate at or above the MP3's: 128 kbps for a 128 kbps MP3, 192 or 256 for music. A higher setting than the source makes the file bigger but cannot add detail back.

If you still have the original recording or a WAV, convert that instead. For your own files, keep the original as the master copy and make M4A or MP3 copies from it.

Which browsers can convert to M4A

Writing an M4A needs the browser's WebCodecs audio encoder with AAC. The page asks the browser before you start and tells you if it cannot, rather than giving you a different format.

BrowserAudio encoderAAC here
Chrome on a computerSince version 94Yes, tested on a Mac
EdgeSince version 94Checked when you open the page
Safari (Mac, iPhone, iPad)Since version 26Checked when you open the page
Firefox on a computerSince version 130Checked when you open the page
Firefox on AndroidNot availableNo
Encoder versions from MDN's browser compatibility data. Which codecs a browser can encode also depends on the device, which is why the page checks first.

Recordings from your phone: voice notes on iPhone, how to transcribe voice notes.

Converting files is a workaround. ParrotNotes skips it.

You are converting a recording so another app will play it. With ParrotNotes the recording starts on your phone, and what you get back is the transcript and a summary, free for 100 minutes of recording a month.

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Related tools

MP3 to M4A FAQ

Sources