8 Best Audiobook File Formats

Writers, you likely love listening to audiobooks–and your readers do too. So here, we’ll examine some of the most popular audiobook file formats.

Readers and writers enjoy the convenience of audiobook files, allowing you to go about your day while also listening to the stories you love. As a writer, it’s wise to format at least some of your writing into audiobook files, allowing you to expand your audience to include those who don’t have the time to sit down and read a book. In addition, audiobooks can allow listeners to slip into another world, exploring the recesses of a fantasy world. With an audiobook, anyone can learn new self-improvement methods while listening to your book during their daily commute.

Whether you or your audience is using an iPhone, a Mac, a Kindle, an iPod, or another of the many mobile devices often used to listen to audiobooks; you must be providing your audiobook options in formats that your audience can access. You’ll want to consider several factors as you choose the audiobook format that makes the most sense for your writing, including sound quality, whether you’re getting the high-quality audio that you want for your listeners, and whether you can make your format available on Audible audiobooks and other popular audiobook sales platforms, and more.

Here, we’ll look at the most popular audiobook formats and how you can decide which option is the best fit for your audience.

Best Audiobook File Formats

Lossy Vs. Lossless Compressed Audio Formats

Audiobook File Formats
Audiobook authors should choose the file format that’s most appealing to their audience and most accessible

There are two basic options for compressed audio files: lossy and lossless compressed audio formats. During the formatting of a lossy compressed audio file, some of the quality of the sound is lost because some data is removed during the compression process. The lossless compression process is more complicated and time-consuming but can result in a higher preservation level of audio quality.

Within each category, there are several file format options. While lossless compression files are indeed smaller than the original file, this type of file is still far larger than a lossy compressed file, as all of the original data is still intact. Therefore, audiobook developers looking to seriously compress their audio files to create faster downloads for listeners may want to choose one of the many high-quality lossy compression formats over a more complicated lossless format.

Most audiobook listeners cannot tell the difference between a lossy and a lossless file. Generally, audiobook authors should choose the file format that’s most appealing to their audience and most accessible using the software commonly used by their target market. You might also be interested in our guide on book formats.

1. MP3 Files

Most people are familiar with MP3 files, as this file format was commonly used for digital music a few decades ago. While there are many types of audio files available for audiobooks today, many people find that the tried-and-true MP3 option is still the best fit. An MP3 file filters out background noise that can be distracting to the listener, which can help create a high-quality listening experience that allows the listener to focus on the information being presented entirely.

MP3 files are compressed, which means that some of the quality of the audio can be lost, placing the MP3 solidly in the lossy compressed audio format category. While this can result in slightly lower audio quality than less-compressed files, most people cannot tell the difference between a compressed and non-compressed file when listening to an audiobook.

2. WMA

You likely remember WMA files if you had a Windows computer in the late 1990s. These audio files were created for Microsoft computers and were one of the first widely utilized lossy compression methods for audio files. There is also a lossless format of WMA, and it’s up to the user to decide whether the lossy or lossless version makes the most sense for their audio project.

The file format has undergone many changes over the past two decades, but the file extension name remains the same despite several upgrades. Regarding sound quality, there’s no question that WMA files are superior to MP3 files. However, while this can create a better listening experience, many platforms do not support WMA files since they’re associated with a single software company.

If you’re creating an audiobook for distribution, it’s key to consider whether your readers can access the file type you’re creating. Since people use various devices, releasing an audiobook in WMA format is not a great idea since this file is accessible solely to Microsoft users.


Introduced over two decades ago in 2001, FLAC is one of the top lossless audio compression formats available today. This type of audio file can compress a file by 60% without losing any of the original file’s data. This means that FLAC files retain all their audio quality despite being compressed too much smaller file sizes.

Unlike many high-quality audio programs, most platforms support FLAC files, making this a great choice if you want to create a high-quality audiobook file for your listeners. Of course, you may need to shell out more cash if you’re creating a FLAC file instead of an MP3, but you may find that the improvement in sound quality is well worth it.

4. Ogg Files

These lossy compression files are known for performing better than both MP3 and AAC formats (more on that shortly) but have unfortunately failed to take hold in today’s audiobook world. While some software programs can read Ogg files, many cannot. As a result, when presented with an Ogg file, many audiobook listeners search for a version of the audiobook that their software can use, rather than downloading or purchasing software that allows their computer, phone, or tablet to utilize an Ogg audio file.

5. AAX

This format is strictly created by Audible, which means that audiobooks formatted in this way can only be enjoyed on the platform. While this is helpful for Audible in ensuring that files are not shared, some users get frustrated that they cannot listen to the audiobooks they’ve paid for through Audible on other platforms without using an Audible converter for their files. AAX is a lossy compression file, meaning that some of the quality of the sound may be lost in the compression process.

Users may find that the sound quality suffers further if they put the file through an Audible converter to listen to their audiobooks on other platforms. If you’re committed to providing your listeners with the highest sound quality possible for your audiobook, you may want to consider using a different type of audio compression.

6. M4A and M4B Files

These are typically lossy files, meaning that some of the quality of the audio may be sacrificed in the name of a smaller file. For example, Apple uses these file formats for unprotected audio available to listeners in the iTunes store. Since these lossy files are small and largely compressed, they’re fast and straightforward for users to download and don’t take up loads of space on their devices. It’s also possible for M4A and M4B files to be compressed using a lossless format. While this is more complicated than compressing these types of files using a lossy format, it may preserve the quality of the audio.

So while audiobook listeners may not notice a difference in lossy vs. lossless M4A format, music enthusiasts may appreciate using a lossless format for their files. M4A and M4B files are nearly identical, and both can provide chapter markings and other parts of an audio file that lend themselves to a positive audiobook experience. In addition, M4B files allow users to bookmark their place within their audiobook, while M4A files do not. This makes M4B files a better choice for many audiobook enthusiasts.

7. M4P Format

Apple uses this audio recording format for music users pay for and download from iTunes stores. If you’re concerned about the possibility of others using your audiobook without proper attribution, you may want to consider using an M4P or other protected file. The sound quality of M4P formats is generally excellent, and today, the file format is not limited to iTunes use. This is a lossy format, so if you’re working to preserve audio quality at the maximum level for your listeners paying for a protected version of your work, you may want to consider a different option.

8. AAC

A lossy compressed audio format, AAC stands for advanced audio coding. This audio recording format was first developed as the next step up from the MP3 format. But, oddly, AAC recording never entirely overtook MP3s as the gold standard in audio recording. Most audio enthusiasts agree that AAC files sound better than MP3 files.

This is because the compression method used for AAC files is more advanced than that used to create MP3s, meaning listeners can hear the intricacies of the reader’s voice that they may miss on an MP3 file. While many audiobooks still use MP3s, other platforms have begun to use AAC as their gold standard. For example, YouTube, iOS, some Nintendo gaming systems, and Android systems use AAC for most audio files.

Considerations When Creating an Audiobook

Whether you’re developing a free audiobook or working to make money from your art, you must keep a few things in mind as you create an audiobook.

  1. Think about digital rights management. Even if you’re releasing a free audiobook and you’re not interested in making a profit, it’s not fair for someone else to use your work and claim it as their own. Talk with your literary agent or audiobook development company about how to protect your work.
  2. Consider your audiobook listeners. You’ll want to be sure you choose a format accessible to your listeners that provides a high-quality audio experience. If your readers have to download a converter to listen to their audiobook, it’s unlikely they’ll ever get past downloading your audiobook file. Be sure to provide them with a file format that can be opened and utilized by iOS, Mac, and Android platforms and the platforms used by standard tablets.
  3. Decide what matters most to you. For example, suppose you’re set on providing your listeners with the highest quality audio possible. In that case, you’ll want to be sure that you choose a lossless audio compression format to preserve the maximum amount of the original file’s sound quality. On the other hand, if you’re more concerned about compressing the file so that listeners can quickly download your book and move on to enjoying the story, you’ll be fine to go with one of the lossy audio compression formats.
  4. Choose a sales platform if you want to profit from your audiobook. If you want your listeners to be able to access your audiobook from iTunes, for example, be sure to choose an Apple-compatible format.
  5. Talk with a professional. While it can be tempting to try to figure out how to create an audiobook on your own, a recording professional will be able to help you choose the best file format for your book and help you work to create the best audio file possible for your listeners.

If you are interested in learning more, check out our guide on the must-have equipment for recording an audiobook!


  • Amanda has an M.S.Ed degree from the University of Pennsylvania in School and Mental Health Counseling and is a National Academy of Sports Medicine Certified Personal Trainer. She has experience writing magazine articles, newspaper articles, SEO-friendly web copy, and blog posts.