What Is an M4B File?

This is an audiobook file, most commonly used with Apple products

What to Know

  • An M4B file is an MPEG-4 audiobook file.
  • Open one with iTunes or VLC.
  • Convert one to MP3, WAV, WMA, etc. at Zamzar.

This article explains what M4B files are, how to open one on your device, and what programs you need to convert one to a different format like MP3, FLAC, WAV, etc.

What Is an M4B File?

A file with the M4B file extension is a MPEG-4 audiobook file. They're often seen used by iTunes to store audiobooks.

Some media players use the M4B format to store digital bookmarks along with the audio, letting you pause playback and then resume later. This is one reason they're preferred over MP3s, which can't save your place in the file.

Lifewire / Theresa Chiechi

The M4A audio format is basically identical to M4B except that those types of files are used for music instead of audiobooks. Apple's iPhone uses the MPEG-4 Audio format for ringtones, too, but those files are instead saved with the M4R extension.

How to Open an M4B File on an iPhone

iTunes is the primary program used to both play M4B files on a computer as well as to transfer audiobooks to an iPhone or another iOS device. You can do this by adding the audiobooks into the program and then syncing your device with iTunes.

  1. Transfer the M4B file to iTunes.

    If your audiobooks aren't in the M4B format, but instead are MP3s, WAVs, etc., skip down to the "How to Make an M4B File" section below to convert them to the right format first.

  2. With the device plugged in, choose the phone icon in iTunes to switch to the iOS device.

  3. Choose the Audiobooks menu on the left side of the program and put a checkmark next to ​Sync Audiobooks.

    iTunes Sync Audiobooks screen for iPad
  4. Pick whether to sync all the audiobooks from your library or just certain ones.

  5. Sync your device with iTunes to send the M4B file to your iPhone, iPad, or iPod touch.

How to Open an M4B File on a Computer

iTunes isn't the only program that will play an M4B file on a computer. Windows Media Player works as well, but you might have to open it first and then browse for the M4B file manually from WMP's menu since Windows may not recognize the file extension.

Another option is to rename the extension from .M4B to .M4A because Windows does properly associate M4A files with Windows Media Player.

Screenshot of several M4B files in Windows 10 that open with PotPlayer

Other multi-format media players that natively support the very similar M4A format, like VLC, MPC-HC, and PotPlayer, will also play M4B files.

An M4B file that you purchase (versus a free audiobook) is likely protected by DRM, meaning that it will only play using authorized computer software and devices. For example, most M4B-based audiobooks that you purchase from the iTunes store are DRM protected and will play only in iTunes and devices authorized via iTunes.

How to Convert an M4B File

Since M4B files are often audiobooks, they're usually pretty large and therefore are best converted with a dedicated, offline free file converter program. DVDVideoSoft's Free Studio is one free M4B file converter that can save the file to MP3, WAV, WMA, M4R, FLAC, and other audio formats.

Zamzar is another M4B converter but it runs in your browser, which means you have to upload the file to their website to have it converted. Zamzar can convert M4B to MP3 online, as well as to similar formats like AAC, M4A, and OGG.

You can't usually change a file extension (like .M4B) to one that your computer recognizes and expect the newly renamed file to be usable. An actual file format conversion using one of the methods described above must take place in most cases. As we mentioned previously, however, try renaming the .M4B file to .M4A, a trick that is very often successful, at least for non-DRM protected M4B audiobooks.

How to Make an M4B File

If you want to put an audiobook on your iPhone, but the audio file isn't in the M4B format, you'll have to convert the MP3, WAV, or whatever format the file is in, to M4B so that the iPhone won't mistake it for a song. Basically, you just have to do the opposite of what you read in the section above.

Audiobook Binder can convert MP3 to M4B on macOS. Windows users can download MP3 to iPod/iPhone Audio Book Converter to convert multiple MP3s to M4B files or even combine the MP3s into one big audiobook.

  • Can I play M4B files on Android?

    Android doesn't support the M4B file format out-of-the-box, but you can download applications like Sirin Audiobook Player to play M4B files. Otherwise, M4B files will need to be converted before you can play them on your Android device.

  • How do you open M4B files on Macs?

    Apple Books, as opposed to iTunes, can open M4B files (audiobooks) on Macs and iOS devices.

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