It is a basic and old question...

There was a "format war" for ebooks (a "Tower of eBabel" for users)... EPUB won?
Wikipedia says that   «... EPUB format is the most widely supported vendor-independent XML-based (...) is supported by the largest number of e-Readers (...). The popularity of Amazon.com's Kindle devices in United States has led also to the prominence of KF8 and AZW » ... It is a truth for this "Ebook publishers and readers" community?

So, putting in other words:

  1. EPUB is a world-wide consensus? It is the most popular, for ebook readers today? We can put all money in this format?
  2. And about the "second place", what is the format? (PDF? MOBI?) This second format is still important for ebook-readers? There are reliable and updated statistics? (2010 example, 2009 example)


The question is about "Comercial + Public Domain" content.

For public libraries and public domain content the perception statistics are changing... People feel that there are "some standard" (EPUB?).

What we have heard (since 2009) in the comercial scenario is «PDF is still the format of choice for most people, though EPUB is getting respectable usage, with Mobi in third», but no reliable statistics about it.

To join "public domain scenario" with "comercial scenario" perhaps another kind of statistics must be also used: a survey like "ebook users read more comercial or public content?"

The world-wide statistics have distinct profile than USA-statistics, but most of the compiled data came from USA.

About replacement of the old and stiff PDF by EPUB, we have heard that "the market" is waiting the advent of HTML5 + CSS3-paged completion (be terminated and official W3C recommendations) and consolidation... How many years?

About reference numbers: how many ebook-titles user have (at Internet) in each format and each scenario?

  • Public domain and open content:

  • Comercial universe: ...? Amazon dominates?


First, a note: I will not be considering PDFs in this answer, because I do not consider PDFs to be ebooks. There are a number of reasons for this, like lack of reflowability and end-user customization options, but the primary reason is that PDFs are not generally sold at sites that sell ebooks--you can't sell your PDFs through iBooks or the Kindle store or whatnot. Others have other opinions, and that's fine—the relevant info is that I won't be considering PDFs here.

In terms of variety of devices supporting the format, epub is the clear standard—it's supported on nearly everything that reads ebooks. When you look at numbers, though, it's a different story: according to an article at Digital Book World, a recent Book Industry Study Group found the following statistics to the question "Where do you typically acquire ebooks?":

Amazon.com website: 51.3%
Amazon App: 15.7%
iBooks/iTunes (Apple): 8.2%
Barnes & Noble App: 6.1%
Barnes & Noble website: 5.7%
All other sources: 12.8%

This means that Amazon accounts for roughly 2/3 of the sales of ebooks, making their proprietary mobi/KF8 format the dominant format.

In essence, there is no "winner" yet, and there is not likely to be any time soon. Apple, Google, Barnes & Noble, and Kobo are enough to ensure that epub will remain alive and kicking for quite some time. With a majority of the sales, Amazon has no impetus to switch to a standard, and they don't appear to be in any danger of losing much market share. Where we are is where we're likely to be for quite a while, which means making two formats: epub and mobi/KF8. fortunately, Amazon has gotten much better at making tools that convert from epub to their format, so concentrating on epub will give you something for Amazon as well with little extra work.

  • 1
    Thanks, this is a good starting point (!)... But it is incomplete without public domain content, and without non-USA e-commerce statistics. Example: As of March 2014, Project Gutenberg claimed over 45,000 items in its collection (but not have any format-download statiscs); SciELO and many other minor public domain e-book projects are also distributing ebooks. – Peter Krauss Aug 24 '14 at 12:51
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    How about software support? As I read around, epub seems to be a much more popular format to create books (even if Kindle coverts it to mobi). – Greg Aug 24 '14 at 19:43
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    Epub is a much more popular way to create ebooks because Amazon's format is proprietary; you can't directly make it. You can only convert to it from epub or a few other formats. – Tom Aug 24 '14 at 20:33
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    @greg: 1000% agreed; that's why I don't ever buy books from Amazon. They're proprietary and terrible. – Tom Aug 27 '14 at 7:52
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    Sure, but given the option, why support a company that does stuff I don't approve of? – Tom Sep 7 '14 at 17:02

Amazon has over 2.8 million ebooks, including nearly all public domain books. See the left hand column, which provides an update to date count of ebooks available: http://www.amazon.com/s/ref=lp_154606011_ex_n_1?rh=n%3A133140011&bbn=133140011&ie=UTF8&qid=1410374478

This 2.8 million books makes things like Project Gutenberg statistically insignificant.

Your quote that "EPUB format is the most widely supported vendor-independent XML-based" is obviously designed to exclude MOBI/Kindle from the mix, because it's not vendor-independent. And sure, outside of Amazon, it is the dominant standard.

But more importantly, why do you want to know?

If the answer is because you want to know what format to publish a book in, versus you want to build an eReader app, versus you're writing a research paper, there are very different implications.

If you're an author publishing commercial fiction, since Amazon has about 65% of the ebook market, you must publish in MOBI to be successful. If you are an indie author, Amazon has an even bigger percentage of the market for indie authors (anecdotally 80+%), and so it becomes even more crucial.

If you are providing an ebook where access is crucial, e.g. a school text book that must be available to all students, then you must publish in both EPUB and MOBI.

Since EPUB and MOBI can be easily converted back and forth, one might argue that the question is irrelevant. Simply provide books in both formats.

  • Hum... a first point... I not know how write right English (I need help of web-translators), but "my book" can add "+1" at Kindle Store counter... By other hand, "my book" will never appear on Project Gutenberg. When we count "any thing" at Amazon we need to compare it with "any thing" at the full-Internet, not only with Gutenberg... – Peter Krauss Sep 11 '14 at 0:38
  • You cited discussions, not reliable sources of statistics... Forbes, that cite Newyorker.com, are good sources, but there are no newer result for @Tom's answer (your 65% is the "51.3%+15.7%" of Tom's). The BISG (Book Industry Study Group cited by Tom) report is good, so what is wrong or what is what's missing? BISG is an U.S. trade association, as Amazon; and Amazon, with others, with focus on non-public contents, was pay BISG to produce the report... Some good results found there, and perhaps other independent report confirm the same results... So, where the "other independent reports"? – Peter Krauss Sep 11 '14 at 14:05
  • Again, I will refer back to: What decision are you trying to make? What is the purpose of the question? Are you testifying in front of a judge? That requires a different level of reliability than say, trying to decide how and where to publish your novel. – William Hertling Sep 11 '14 at 23:19
  • We develop software and offer services for "content management/styling/transform"... Some software need a 2-year plan... What will the scenery in 2 years? How will the market and the "reading habits"? Our main customers are public domain content producers, for non-US readers... This is our reality, and is the same for many middle/small company around non-US-world. – Peter Krauss Sep 12 '14 at 0:38
  • If that's your need, then it's a complete non-issue. Decide on a base platform (and personally, I think EPUB is the one to use) and then convert to the other for distribution to nearly 100% of the market. – Auspex Sep 16 '14 at 0:58

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