Important Notice: as of midsummer, 2021, this article is outdated. Please refer to our updated article for the latest, greatest, and accurate information. Again, this article contains outdated and not-useful information; refer only for historical purposes.  

About eBook Formats

One of the questions that we are often asked is, "what is the best eBook format for Kindle? I'm not always sure what question I'm being asked.  Is the person asking to find out what file format they should upload to Amazon? Are they asking what's the best way to make a book for the Amazon-Kindle ecosystem? Really, there are only two eBook formats that are still remaining in the USA, and, when you look around, in the world. Those formats are:

• ePUB: which stands for ePUBlication (clever, eh?), which is used by B&N, iBooks, Sony, KoboBooks, and Google, and,
• MOBI format, which is the preferred Kindle file format.

If you've Googled, you've likely seen all sorts of claims, ranging from some folks telling you that you can put an ePUB on Kindle, to the idea that using Word is the best "Kindle eBook format." The bottom line is, the files that Amazon sells to its readers are, by and large, a single file format, called "MOBI."

What Format Does Kindle Use?

Now, if you've run across various forums, you may have seen people refer to AZW format, or AZW3 format. The former is the actual, final, encrypted Kindle format that is dispensed from the Amazon store, to your Kindle as a purchased book. That's not a format that you can make yourself. And, even if you could, you can't upload that format at the KDP, the Kindle Digital Publishing platform. The latter, AZW3, is a file format, created to emulate what's called "KF8," (the more-advanced Kindle formatting) by a piece of free library software called Calibre. However, just like AZW, you can't upload an AZW3 file format at the KDP. You can certainly make a file in that format, and side-load it to your own Kindle device, but you can't publish it. Obviously, that format, then, lacks utility.  Fine for personal use, but useless for publishing.  If someone starts yammering away at you, talking about how you can convert your file to AZW or AZW3 format, for the purposes of publishing--that's not someone to whom you should be listening.

Curious As To Why You Might Ever Want or Need an ePUB File?  Read On!

How Can A MOBI File Be Anything Like A CAKE?

When we’re called by prospective clients, we’re asked a lot of questions. Some of them are about layout, some about functionality, and some are simply what seem to be practical questions, to the typical person or new eBook publisher.

One of the things that I’m often asked is “Why do I need an ePUB file? I only want to publish to the Amazon Kindle program, which uses MOBI, so why do I need to pay for an ePUB?”

What is an ePUB File? What's in a MOBI File?

As background, to address this, it helps to know that of all the major retailers, Amazon uses an eBook format called “MOBI,” and all the others (B&N, iBooks, KoboBooks, Sony, etc.) use the other major eBook format, “ePUB.” Basically, the eBook DNA of both formats is 98% identical; only at the very end of the process does the bookmaker make the decisions that end up creating an ePUB file versus a MOBI file, or vice-versa. So, by and large, it’s not twice as much for a company to give you both formats (and if anyone tells you that—find a different formatter!); it’s only a bit more money, as a large part of the work is the same.

The exception to this is what’s called “Fixed Layout” or “Fixed Format,” but that’s a topic for another day.

BUT:  MOBI Kindle Files are not editable.  

What most folks don’t know is that a MOBI Kindle file is not editable. When I tell people that, they naturally ask me, “but, if I want to make changes, how does that happen?” So, here’s the real deal on the basics between ePUB and MOBI:

A MOBI file is a finished, completed product. It is, essentially, like a Cake. When it’s finished, it’s great—but if you wanted to, you couldn’t take that cake apart and get your ingredients back. You couldn’t decide that you wanted to replace (say), half your white sugar with brown sugar. You can’t get your eggs, your flour, your sugar or flavorings back. It’s great, but it’s CAKE, not cake ingredients. If you decide to change your cake, you have to make a whole new cake, from new ingredients.  

(If you want to get techy—a MOBI file is a binary database file that is built from its HTML source).

But, What If You Need To Change Your MOBI File?

But an ePUB file, on the other hand, isn’t just CAKE. It’s a cake that you can disassemble, if you need to. You can get your flour, your eggs, your sugar and your flavorings back from your ePUB. Your ePUB exists in two ways simultaneously; it’s both a finished book (cake!) and the ingredients. This is because an ePUB format isn’t like a MOBI format—it’s a bunch of files (ingredients) zipped into a unique format (ePUB). The “book” exists when it’s zipped into that special ePUB format. But if you know how, you can simply open up that formatted book, and you can add sugar, eggs, flour (text, formatting, other elements), make your changes, and zip those ingredients right back up into…a BOOK. It’s a bit like magic. You can wave your wand at an ePUB, and say “EPUB-liarmus!” and you can take it apart, and then put it right back together as you see fit.

Most professional eBook conversion and formatting firms will use an ePUB, or the constituent parts of the ePUB, to build the MOBI file. What does this mean for you, as a publisher? Well, think about it: if your formatting firm only gives you the MOBI file (cake!), and you later decide that you want to make changes—what do you do? You’re forced to go back to the same firm. You don’t have your source materials (your ingredients) any longer. I’ve even been told by some folks who’ve come to us that some companies will charge you as if it’s a brand-new book—a build from scratch, rather than simply revising the files that they must have in their archives.

So, don’t forget: you WANT an ePUB. Firstly, you never know when Amazon might decide to use ePUBs; you never know when you might want to change your ingredients; and third, heck—you’re paying for your eBook to be created. Make sure you get your own source files, for your future use.

And that way (yes, wait for it!)...you can have your Cake, and eat it, too. 

Who Says Typography Matters?

The Stanford Persuasive Technologies Lab did a study, and found that despite the naysayers, typography matters.  Not merely in terms of persuasiveness--in terms of credibility. What did their study find out?

The study found out that "participants made credibility based decisions...based upon...overall visual appeal."  And what elements went into determining "overall visual appeal?"  The very first element was typography, followed by layout, font size, and color scheme.  Why does this matter to you, as an author? 

Below is a list of 28 websites, ezines, and blogs, whose contributors post more in-depth reviews of featured books and ebooks. Again, the sites are ranked by Alexa number: the lower the number, the more popular the site. You can submit your work to all of them, although it goes without saying that a submission will not necessarily result in a review, favorable or otherwise!

• http://blogcritics.org/books/ 12,356: Features book reviews and ebook reviews, separately.
• http://dearauthor.com/wordpress/category/ebooks/ 110,388: A site that reviews romance books, with a smattering of other genres.
• http://www.bookslut.com/ 207,831: A monthly web magazine and daily blog dedicated to reading: news, reviews, and commentary, and unofficially affiliated with NPR. To submit a book: http://www.bookslut.com/contact.php
• http://blog.booksontheknob.org/ 246,176: A site featuring and alerting readers to bargain reads, free ebooks, and providing ebook reviews. For review: http://blog.booksontheknob.org/p/about-this-blog-and-contact-info.html
• http://kindle-author.blogspot.com 284,485: A blog for self-published kindle authors, run by a self-published kindle author. He provides author features, interviews, posts "sponsored posts" by guest writers, and opportunities to advertise on his site.
• http://www.coffeetimeromance.com/Welcome.html 368,716: A site that reviews romance novels. http://www.coffeetimeromance.com/reviewsguidelines.html
• http://theunreadreader.com 696,089: A blog that reviews bound and e-books, focusing on chick lit, contemporary, dystopian, paranormal, romance, urban fantasy, and young adult; does not accept nonfiction or self-pub. Submission directions here: http://www.theunreadreader.com/p/review-policy.html
• https://bestsellersworld.com/ 946,785: A network of reviewers that provides book reviews and giveaways. BestSellerWorld---get reviewed
• http://www.kindleobsessed.com/ 1,082,187: A blog that reviews self-published and indie authors and posts lists of free ebooks. Submit for review here: http://www.kindleobsessed.com/review-request/
• http://www.mrsgiggles.com/index.html 1,151,918: A site that reviews ebooks, mostly of the romantic fiction genre, and sometimes movies and music.
• http://bookdout.wordpress.com/ 1,429,032: A blog that reviews print books and ebooks (that can be accessed on ipod touch), with a preference for general fiction, women's fiction, cosy mystery, psychological thriller, murder mystery, crime, humor, paranormal/urban fantasy, and romance.
• http://candysraves.com/ 1,649,793: A blog that reviews books and ebooks, with an emphasis on memoirs, women's fiction, light paranormal, crime novels, time travel novels, horror/suspense/thriller, and selected YA. Reviews are posted on the site, as well as on Goodreads, Smashwords, and Amazon.
• http://thebookbuff.blogspot.com/ 1,705,165: A blog that reviews all books and ebooks of any genre but erotica. Submissions: http://thebookbuff.blogspot.com/p/review-guidelines.html
• http://acozyreaderscorner.blogspot.com/ 1,773,601: A blog that reviews books in hard copy (preferred) but also ebooks on a limited basis, with a focus on women's fiction/chick lit, romance, literary and historical fiction, Christian fiction, YA, children's literature, memoirs, and cookbooks.
• http://bitsybling.blogspot.com/ 2,130,000: A blog that reviews books and ebooks of any genre. Submissions: http://bitsybling.blogspot.com/p/review-policy.html
• http://booklog.eternalised.net/ 2,586,781: A book review blog featuring adult and YA fantasy novels, paranormal, supernatural, and historical genres. http://booklog.eternalised.net/review-policy/
• www.dailyebookreviews.com/ 2,951,890: A blog that reviews fiction ebooks, with an emphasis on science fiction, horror, fantasy, and thrillers, and spotlights an author weekly.
• http://twoendsofthepen.blogspot.com 3,118,843: Fantasy/sci fi co-writers team up to review books, conduct author interviews, and post guest blogs. Submit for feature and/or pay for a slot on a "spotlight page" here: http://twoendsofthepen.blogspot.com/p/about-me.html
• http://busybeesbookreviews.blogspot.com/ 3,418,571: A blog that reviews books of most genres and offers author interviews. Submission information: http://busybeesbookreviews.blogspot.com/p/review-policy.html 
• http://thebooxreview.com/about 3,705,955: A site that posts of reviews of new ebooks by an in-house reviewer, and posts readers' submitted book reviews.
• http://www.thesundaybookreview.com/ 3,947,099: A site that reviews thriller, crime, true crime, and mystery, as well as provides indie pub news, guest posts, and interviews.
• http://spaldings-racket.blogspot.com/ 3,990,280: A blog run by author named Nick Spalding who reviews books of all genres. Submit your books here: http://spaldings-racket.blogspot.com/p/submitting-your-book-to-spaldings.html
• http://smashwordsreviewed.blogspot.com 5,009,611: A blog that features indie authors, reviews new books, interviews authors, and hosts guest reviewers of all genres.
• http://www.ebookaddictreviews.com/ 5,406,299: A team of reviewers that reviews romance ebooks.
• http://thecajunbooklady.com 6,227,261: A blog featuring book reviews, author interviews, and giveaways. Submit books here: http://www.thecajunbooklady.com/p/reviewing-policy-ftc.html
• http://elizabethswigar.wordpress.com/ 8,056,568: A blog dedicated to reviewing Kindle formatted ebooks, open to all genres, but particularly interested in historical fiction.  http://elizabethswigar.wordpress.com/submit/
• http://novelcritic.com: Reviews published and self-published novels of any genre.

Give 'em a try, and let us know if any of these are particularly fabulous--or particularly bad.  We like to keep our clients and folks who drop by updated!  Thanks!