EPUB Vs. MOBI Vs. PDF: Which File Formats Should You Use When Self-Publishing?

Expert publishing blog opinions are solely those of the blogger and not necessarily endorsed by DBW.

author, self-publishing, epub, mobi, ebook, pdfSo you’ve written a book and you want to get it out into the world. You’ve decided that self-publishing is the way to go, but you’re not really sure how to turn that book on your computer into something that can be read by an eager public.

In this post, we will show you the three most common file standards in self-publishing and let you know how you can easily create your book in these formats. Ready?

EPUB: One Format to Rule Them All

An EPUB file is the most widely accepted ebook format on the market. It’s the industry standard, used by Apple, Kobo, Barnes & Noble and Google for their ebook distribution platforms.

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 most of the publishing industry has rallied around it as the 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?

MOBI: The Kindle Exception

Amazon’s Kindle Store is the biggest ebook retailer in the world, and by quite a long way. In 2015, it was responsible for more than 70 percent of ebooks sold in the US. So you can see why authors are pretty keen to get their books into the Kindle Store.

But what does this have to do with the popular DJ and Grammy-nominated musician?

As it turns out, the ebooks you buy on the Kindle Store will have the file extension .mobi—but are actually formatted to a proprietary standard called AZW. These files are protected by Digital Rights Management (DRM), which “locks” the book so it can only be read on devices associated with your account.

If that last paragraph sounded complicated, don’t worry: Amazon’s Kindle Direct Publishing service has an integrated tool which will happily accept EPUB files.

PDF: Your Single Solution for Good Ol’ Fashioned Printed Media

Perhaps the most cost-effective way of selling physical copies on a small scale, self-published 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. The two most popular POD services are IngramSpark and CreateSpace, the latter of which is—would you believe it—an Amazon company (“Amazon: we invented books”).

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, not using the RGB color model.

If you’re a big fan of file formats, you’ll be pleased to know that the Reedsy exports PDFs with the Adobe PDF/X-1a:2001 format: a standard used by most professional printers.

So What Platforms Require Which Format?

If you’re printing physical copies with a POD service, you will need a print-ready PDF. For ebooks, you will be able to upload an EPUB file to any platform, including the Kindle store. From a practical point-of-view, those two are the only two formats you’ll need to work with.

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14 thoughts on “EPUB Vs. MOBI Vs. PDF: Which File Formats Should You Use When Self-Publishing?

  1. Derek Cross

    There are two versions of ePub – reflowable text ePub (can be viewed on any device and easily converted to mobi) and Fixed Layout ePub, a limited number of devices can view these.
    Re “multimedia content like video and audio clips”. Not all devices can recognise these.

  2. Michael W. Perry

    A few remarks from someone who has been in this a long time:

    First, publishing via InDesign currently gives you the best options. That document that’ll be a top-quality print version can also be used to create a fixed-layout epub that looks virtually identical on devices that support it and a reflowable epub for the others. Get ID via Adobe’s single-app $20 Creative Cloud plan, and they’ll also host a website for you. If you’re seriously into writing, that $240 cost is a bargain. It’s less than $! a day.

    Second, writers need not choose between epub and mobi. Create an epub and supply that to Amazon for conversion. I leave it to Amazon to make that conversion viable. Eventually, Amazon will have to come around and bring up-to-date their own plug-in for ID.

    Third, this remark made me wonder if this article was a belated April Fool’s joke:

    “EPUB is a remarkably flexible format that supports a wealth of features…. The latest version, EPUB 3, will even permit you to add multimedia content like video and audio clips.”

    EPUB is actually a remarkably impoverished format, roughly HTML circa 1995. It handles formatting beyond simple fiction poorly. I’ve got several print books I can’t turn digital because they’d look awaful. Those responsible for EPUB standards seem so cluelessly locked into a webpage mindset, that they’ve failed to address the main distinction between webpages and ebooks. People scroll webpages. They page through ebooks. And yet EPUB doesn’t nothing to format pages attractively. It does nothing to lay them out attractively or to allow those laying out an ebook to do that. Those doing layout are forced to either limit the scope of what they do or endure ebooks that’ll look hideously ugly.

    And multi-media content? Why are we still talking about that? I worked for Microsoft back in the late 1980s when multi-media content, enabled by the space on CD-ROMs, was the buzz. It failed then. It’s failing now for two primary reasons:

    1. Readers want to read. They don’t want to be interrupted by audio and video. They would appreciate accompanying graphics, but EPUB handles those so poorly, it’s hardly worth the effort to include them.

    2. Creating decent quality audo and particularly video that’s relevant to the tale, not just tacked on, is hideously expensive. For the cost of just two or three minutes of tolerably done video, a publisher can employ the services of a talented editor who’ll do more for a reader’s enjoyment than some brief video.

    Yes, A/V will allow some tacky, tasteless publishers to inject advertising into their books like the horrid auto-play video ads on some webpages. But that’s not something to get excited about. It’s a vile trend to be fought. Books are one of the few ways in our society we can avoid the intrusive presence of advertising. We need to keep it that way.

    –Michael W. Perry, Inkling Books

    1. Emmanuel Nataf

      Hello Michael,

      All good remarks. We were not making judgments about the formats themselves (I agree with you, ebooks are pretty ancient in general) but more trying to give an overview of the different formats for authors who might not know them yet.

      Regarding InDesign, it’s definitely the best typesetting tool. However, we found that it was too sophisticated for most authors, which is why we built the Reedsy Book Editor (completely free). It creates beautifully designed books in seconds: https://reedsy.com/write-a-book. Feel free to share your thoughts about it with me directly, I’m at emmanuel at reedsy.com.


      1. Virginia Anderson

        I’ve been formatting my own pdfs of novels (no graphics) in InDesign, and I’ve actually found it quite usable. In fact, on my blog, I’ve been doing a series called “InDesign Beginner’s Cheat Sheet” that separates what someone doing a novel interior really needs to know from the intimidating options in InDesign. Here’s the first post: https://justcanthelpwriting.wordpress.com/2016/05/17/indesign-for-book-formatting-cheat-sheet-i/
        I’d love feedback. I’ve gotten a lot better at incorporating screen shots since these first posts; down the road, I want to pull these together into a pdf for beginners like me. Bottom line: if I can, you can.

        1. Nancy Foster

          I have this program because my sister is a graphics designer who ends up asking me to lend her my laptop every now and then when her ancient laptop gets busted. I have an image heavy computer software manual I wish to publish doon but the images look horrid if you convert to mobi via Calibre. Is InDesign a viable solution? Is it eady to use? I use photoshop decently despite lacking a designer college background but Illustrator is impossible to learn on my own. Thanks!

    2. Ben

      Ah, I think you’re getting EPUB confused with the (ancient) Open Ebook format from the 1990s, which is what Amazon’s Mobipocket is based on. EPUB 2.0.1 (the old standard) is based on HTML4 (XHTML 1.0 Transitional or Strict) and CSS.

      The current standard, however, is EPUB 3.0.1 and its HTML 5 with XML (sometimes referred to as XHTML 5) plus CSS 2.1 (all of it) and parts of CSS 3 (which makes sense if you understand what’s happening with CSS versioning of components). It does permit limited use of javascript, but nothing can be only accessible that way (i.e. all content must be accessible without running a script).

      As for multi-media (particularly audio) in books, there are a couple of answers: accessibility and education. You might not want a “talking book” and that’s okay, you don’t have to like them, listen to them or publish them; but a standard which makes it possible is still a good thing. Which is why the DAISY Consortium backed EPUB 3.0.

      I suggest you actually read the IDPF specifications before commenting on what EPUB is or isn’t capable of. You never know when someone who has read them might come along and prove you don’t know what you’re talking about. I’ll grant that a lot of ebooks have awful typesetting, but the fault is in the production and the CSS (or lack thereof).

  3. freddie

    As it turns out, the ebooks you buy on the Kindle Store will have the file extension .mobi—but are actually formatted to a proprietary standard called AZW. These files are protected by Digital Rights Management (DRM), which “locks” the book so it can only be read on devices associated with your account.

    And Calibre unlocks those files so they can be read on non-Kindle devices

      1. Ben

        That depends on which country you’re in and whether there are any exceptions to DRM. Most countries permit the removal of DRM for a variety of reasons, usually including to facilitate accessibility (e.g. screen readers), for research purposes, for archiving and there’s often one or two other exceptions.

        Unless, of course you’re asking whether or not DRM is legal and then the answer is the same; it varies according to jurisdiction. For instance, technically DRM would fall into the category of third line forcing in Australian law and be illegal (according to the Competition and Consumer Act, formerly the Trade Practices Act). However, the MPAA bitched and moaned about that when the law was about to be used to get rid of DVD regions and the government rolled over for America (again) and simply don’t enforce that law … against American companies.

  4. Joel Emmett

    Question: Does MOBI accept multimedia embeds? If I submit an EPUB book to Amazon with embeds, will they be stripped out?

  5. Julanna

    I would add that if a book was being distributed from your own webspace rather than / instead of one of the usual platforms the author may want to consider providing a web page / html version as well. Some people don’t use e-readers and will read it on a computer screen instead. It’s nice to make it easy for as many readers as possible.

    And audio is becoming more popular I think so maybe that format could be included as well. (Obviously sans extra content.)

    For the multimedia comment: it depends on the content of course. Certainly fiction won’t need it but some non-fiction may benefit from the additional material, as do some web pages, but fiction really should be kept as simple as possible to help make it as compatible as possible across a range of devices that will all treat the e-book in different ways. If extra content or fixed format is provided a note on the site saying so would be helpful so readers aren’t frustrated by trying to read it on a small e-reader.

  6. Ambient

    Julanna: “Some people don’t use e-readers and will read it on a computer screen instead.” But are you conflating e-readers with dedicated hardware devices? What’s wrong with the plentiful e-reader applications on computers and phones?

    I disagree with most of the comments by Perry about EPUB. I couldn’t be more pleased with my EPUB layout on Kindles, iPads, PCs and phones. EPUB enables the reader to choose font, font size and other details, and it accommodates the widest variety of applications and devices. It would be absurd for a book designer to restrict that flexibility.

    I did not turn my EPUB over to Amazon for a conversion service; after creating the book in Sigil — an awesome EPUB authoring system — I converted it directly to MOBI in Calibre and got precisely the product I wanted.

    1. Julanna

      Hi Ambient, by e-readers I did mean the dedicated hardware device. Not a thing wrong with e-reader applications but there’s nothing wrong with web page version as well. There may be less will read like that but my comment was simply about catering to as many people with different formats as possible and if you are making an e-book you have the html as a part of the process. It doesn’t take much to take that page and make it presentable for reading in a standard browser. I guess I’m used to looking at Gutenberg, they supply several formats, eg http://www.gutenberg.org/ebooks/1661



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