ePUB versus MOBI [Different eBook Formats Explained]


Amazon is by far the largest e-book retailer in the world, so it’s no surprise that it has a proprietary Kindle format for e-books sold in its store and read on its e-book readers. If you buy books for your Kindle from other e-book retailers, you should know the differences between EPUB and MOBI files and how to convert them.

Key points to remember:

  • EPUB is the most widely accepted and functional e-book format. MOBI and AZW3 are Amazon’s proprietary formats used for Kindle devices.
  • If possible, you should always leave the books in the original format.
  • Kindle e-readers cannot read EPUB files, which means you must convert them to MOBI or AZW3. All books purchased directly through Amazon will be automatically converted if needed.

We’ll start with a brief overview of file formats and the pros and cons of EPUB and MOBI, but if you just want to learn how to convert them, you can skip to the end. If you’re looking to convert a PDF file, you can check out our PDF format guide instead, although the steps detailed below will work for the most common document formats, including PDF books.

  • MOBI files are much larger than other eBook files due to the way the format is designed to be compatible with all Amazon Kindle devices. A MOBI file will contain the book itself, which is usually just an EPUB file and several converted files compatible with all versions of the MOBI (or AZW3) format.

  • Kindles primarily use two file formats: MOBI and AZW3. For files other than e-books, Kindles can also read DOC and DOCX, PDF, TXT as well as HTML and HTM files. They can also open certain types of image files such as JPG, PNG, BMP, and GIF.

  • No, Kindle devices cannot read EPUB files. If the book was purchased through Amazon, it will be automatically converted to MOBI or AZW3, but if it’s from another source, you’ll need to convert it before your Kindle can open the file.

EPUB vs MOBI: What are e-book file formats?

A file format is essentially a standardized way of encoding information so that it can be understood by all devices and programs. If you’ve used any type of computer, chances are you’ve heard of formats like JPG, PDF, or MP3.

Typically, file formats are designed to hold a specific type of information, such as an image, sound, video, or as we’ll discuss here, e-books. There are different ways to encode e-books, but by far the most common e-book formats are EPUB, MOBI, and the descendant of MOBI, AZW3.

What is the EPUB format?

Developed by the International Digital Publishing Forum, EPUB is the most widely accepted e-book format. The format is open source, has many composition and layout options, and supports highlighting, bookmarks, and even media files such as images and videos.

EPUB files also tend to be much smaller than MOBI and PDF files and are directly compatible with services like Google Docs. Graphically intensive e-books particularly benefit from the EPUB format, as these types of books can quickly bloat in size when using MOBI or AZW3 and become completely unusable as PDFs.

What is the MOBI format?

MOBI is mostly a legacy format at this point. Although you can still find it on third-party download sites, it has been replaced as Amazon’s official e-book format by AZW3. This file format is developed internally by Amazon and is essentially an enhanced MOBI with additional DRM capabilities along with updated layouts and composition.

amazon mobile size

Amazon’s in-house format dates back to a company called Mobipocket which Amazon acquired in 2005.

Since the main focus of MOBI is compatibility with all Amazon devices, the files are usually much larger than EPUBs. As Amazon has continually released new Kindle devices, it has also updated its proprietary file format to accompany new hardware.

This means that for a MOBI file to be backward compatible with each Kindle device, it must contain multiple copies of the book that conform to each version of the MOBI or AZW3 formats.

Should you use MOBI or EPUB files?

If you’re using something other than a Kindle or the Kindle app, EPUB is the best format. The only real reason to use MOBI is compatibility with Amazon’s e-reader and app, but otherwise it has no advantage over EPUB, which is a widely accepted format that is much easier to use. to work.

That said, if the book you want to read is already in the form of a MOBI file, there is no reason to convert it to EPUB unless your device is incompatible with MOBI files. This could be the case, however, as most third-party e-readers and reader apps such as Adobe Digital Editions are not compatible with Amazon’s internal format.

How to convert EPUB and MOBI

Converting books between EPUB and MOBI formats is incredibly easy. A simple Google search will show that there are dozens of free converter websites, and all you have to do is go to one of the best ones, upload your EPUB or MOBI file and click ” convert”.

convert epub book

Browser-based converters are more than capable of converting most MOBI and EPUB books.

This kind of quick and easy browser-based solution will work for the vast majority of books. That said, if you’re trying to convert a particularly large file, perhaps an epic job or loaded with 1,000-page images, you’ll likely run into the file size limits on those sites. If so, you can download Calibre, a free e-book management program.

How to convert EPUB and MOBI files with Caliber

The best way to convert large MOBI or EPUB files as well as manage your eBooks in general is with Calibre. The software is free to download and allows you to convert all kinds of document and e-book files.

  1. Download and install Caliber

    Go to the Caliber website and click on “Download Caliber.” Run the downloaded file and follow the instructions to install software.

    kindle drm removal download online
  2. Add your book to Caliber

    Once Caliber is open, click the button in the top left corner that says “Add books.” To select “add books from a single folder” and find the file you want to convert in the file selection window that opens.

    add kindle files manually
  3. Select the book and convert

    Now that you can see the book in your library, select it and click the button at the top of the window that says “convert books”.

    caliber step 3
  4. Choose conversion settings

    This will open the conversion settings, where you can adjust metadata (such as title, author, publisher, and series), change cover image, and set output format. There are plenty of advanced options located in the left menu, but for now all you have to do is set the output format in the upper right corner to what you want it to be and click “OK” in the lower right corner.

    caliber step 4 (epub)

Other Notable File Formats

Besides EPUB, MOBI, and AZW3, e-books will sometimes be available as PDF files. It’s not a great way to format an eBook because PDFs are inefficient, don’t handle larger documents well, and don’t display well on mobile devices. AZW3 is also sometimes referred to as KF8, KPF, or KFX, but these names simply reflect updates to the AZW3 format.

amazon kindle paperwhite other formats

Although it is the most widely supported e-book format, Kindle apps and devices do not natively support EPUB.

Final Thoughts

That’s it for our guide to MOBI and EPUB files as well as e-book file formats in general. Hopefully, you now have a better understanding of what these terms mean and what kind of file types you want to use with your eReader or reading app.

What did you think of the guide? Did we miss something that you think we should have covered? Is there a better e-book converter program that you would recommend? Let us know in the comments below. Thanks for the reading.

Let us know if you liked the post. This is the only way to improve ourselves.




Comments are closed.