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Blog > Book Design, Understanding Publishing – Posted on November 17, 2017

EPUB vs mobi: Which eBook Format Should You Use?

EPUBs and mobi files are the most common ebook formats in the world. If you're a self-publishing author looking to distribute your title in ebook stores (which you should: some of the most voracious readers own e-readers) you will need to know a little about these two file types. In this post, you will learn everything you need to know about the Clash of the Titans that is epub vs mobi.

What is an EPUB?

An EPUB file is the most widely-accepted ebook format on the market. It’s the industry standard, used by Apple, Kobo, Barnes & Noble, Sony and Google e-readers.

A free and open standard based on HTML (much like the files your web browser would read), EPUB is a remarkably flexible format that supports a wealth of features. It can optimize a book’s text to fit your device, embed images, and allow for bookmarking, highlighting and text-to-speak. The latest version, EPUB 3, will even permit you to add multimedia content like video and audio clips.

All around, it’s pretty great — which is why the publishing industry has rallied around it as its ebook format of choice. If you want to upload your book directly to almost any ebook retail platform – through Kobo Writing Life or Nook Press, for example – or use an ‘aggregator’ like Smashwords or Draft2Digital, you will need to have an EPUB file.

So what’s stopping EPUB from being the single digital book format?

What is a mobi file?

Does Moby prefer mobis to EPUBs? One can only assume.

Mobi files are the ebook files used exclusively by Amazon’s Kindle Store. Or, if we're staying up-to-date, the actual proprietary standard is now called AZW. The major difference between mobi files and EPUBs is that the Amazon format is protected by Digital Rights Management (DRM) which ‘locks’ the book so it can only be read on devices associated with your account. Amazon is the largest ebook retailer in the world by quite a long way: in 2015 they were responsible for over 70% of ebooks sold in the US. This massive market share is part of the reason why they can insist on using their own format.

To summarize: the Kindle store uses mobi files, and every other major ebook uses EPUBs. But, if you're an author looking to export an ebook file that's compatible everywhere, what can you do? Well, the short answer is that you should export an EPUB, for reasons we'll look at right now.

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What's the easiest way to convert EPUB to mobi?

If you have an EPUB that you want to convert to mobi right now, you can simply put it through our EPUB to mobi converter! You'll get a beautiful new mobi file in your email inbox within minutes.

Amazon's Kindle Direct Publishing platform also has an integrated tool which will convert EPUBs into mobi files. The Reedsy team ran countless tests and found the conversion to be pretty seamless.

Finally, if you export an ebook using the Reedsy Book Editor, you will have the option to choose your ebook retailers. If you select 'Amazon' as an option, you will download your book in mobi format.

When should you use PDF files?

The PDF, which has remained one of the most popular document formats since its debut in 2001, is still widely used in publishing for two purposes.

Perhaps the most cost-effective way of selling physical copies on a small scale, self-publishing authors commonly use what’s called a print-on-demand (POD) service. Instead of ordering a print run and filling a warehouse with paperbacks, copies will only be printed as and when they’ve been purchased either by individual buyers or a bookstore.

The two most popular POD services are IngramSpark and KDP Print (formerly CreateSpace), the latter of which is — would you believe it? — an Amazon company.

A print-on-demand book, sourced from a PDF file.

For this, you will need a file that contains strict definitions of your book’s layout and content – which is why we use PDF files. There are countless different types of PDF out there but for our purposes, the format will need to a ‘print-ready PDF’ to make it compatible with printers.  Any hyperlinks will be removed and your image colors will be expressed in CMYK, and not using the RGB color model.

Graphically Intensive eBooks

Both EPUBs and mobis are great at handling text-intensive books like novels, memoirs and some non-fiction books. They are, however, less awesome at dealing with books that have a lot of images, graphs and photos — art books and travel guides, for example. If you need your ebook to look exactly the same as the print version, you may wish to sell it as a PDF, which will ensure fidelity across all devices.

The downside is that basic black-and-white Kindles (and e-readers like it) will struggle to display them well — as these PDF books will tend to be fixed-width. Unlike an EPUB file, where the text is "reflowable" and will adapt to the shape and size of your device, reading a small-print PDF book on a Kindle Paperwhite is nothing short of a chore.

Creating EPUBs and print-ready PDFs

Reedsy offers a free online book editing tool that lets you professionally format a book with no training required. Once you’re happy with how it looks, you can export your book for free as both EPUB and print-ready PDF files!

To find out more about how the Reedsy Book Editor can help you publish your own book, click here.

To learn more about how to set up your ebook on the different retailers, read our master guide on ebook publishing platforms.

If you have any thoughts or questions on choosing a file format, drop us a message in the box below.