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PDF vs. EPUB vs. Mobi Format Download Comparison for oreilly.com

UPDATE: Additional view showing relative volume, rather than percentage.

I’m honored to have been elected to the IDPF Board of Directors, and will use the occasion to share some interesting data about download formats from oreilly.com.

For most of our titles, we offer three different (DRM-free) formats: PDF, EPUB, and Kindle-compatible Mobipocket. PDF continues to be the most popular format, though it’s losing ground to EPUB (and to a lesser extent, Mobi). We’ve been tracking which of those three formats customers actually download after purchasing (it’s of course possible that they download multiple formats), and here’s the breakdown over the last 16 months:


And here’s the same data in terms of relative volume, rather than percentages:

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Comments: 17

  1. there’s a huge confound in the data here.

    specifically, it’s far easier to get the text —
    the text, the whole text, and nothing but the text
    — out of an .epub file, in comparison to a .pdf.

    i bet if you offered a text-based format as well,
    you’d find that _that_ was a hugely popular thing.

    surely with all your fancy .xslt converters,
    you could find a way to output to se-text…
    or markdown. or even z.m.l. (zen markup language).

    give it a try. show you have some courage, guys.


  2. Bowerbird that’s a superb idea. There’s always some concern about reuse, but we’re aiming to provide a service
    so good it’s simpler to come to us than go around us.

    It’s not trivial to get a new format up and deliverable but if customers would find value in it, I’ll certainly jump to Implement.

  3. Howdy – any insight into why PDF remains so popular?

  4. OK, man, have to ask.

    I’m looking at that trio of little squiggly lines there. You know, showing what appears to be a severe decline in ebook sales, starting in October (the “relative volume” graph, if that’s unclear).

    Now, Wiley just reported annual sales that were flat to slightly higher. And, while there is certainly seasonality in certain genres (smut, for example), there was no corresponding dropoff in O’Reilly ebook sales for October ’08, so I don’t think that would explain it.

    Given that October was roughly when you guys announced the controversial takeover of Microsoft Press, and a certain high-profile recent exit from the O’Reilly family, umm, anything you’d like to tell us about how sales have gone lately?

    Really puzzled. Are your customers all buying from Bookworm, Aldiko and Scribd instead?

    /Actually, even outside the Kindleverse, where Olympia has between 10-25 of the top-selling works in smut at any given hour, November was good this year, though it’s largely because of content. I not only issued a really good one, I sent an email… productivity was helped by me skipping Miami for family reasons.

  5. @Robert — My guess about PDF is that most people are still reading these on PCs, and in general PDF is a much more familiar format than EPUB.

    @Mr. Moynihan — I can see why you would think there was a “severe decline” in October, but that’s because there was a “severe increase” in September when we ran a month-long promotion for customers who had previously registered their print books with us, to buy the ebook version for $4.99. The response was very strong through the month of September (as you can see from the graphs) until we stopped the promotion. So October was reverting to the steady trend throughout the year (4% per month, a 60% CAGR). Our ebook sales are already more than 80% ahead of full-year 2008 sales, and show no sign of slowing.

    We certainly didn’t “take over” Microsoft Press. This is a distribution and co-publishing relationship, and we’re proud that Microsoft chose to work with us over other prominent tech book publishers.

    As for the “high-profile recent exit” I assume you mean Keith Fahlgren, who I’ve worked with for 5 years, and who I respect deeply. I’m familiar with some details of his new role with Threepress and Ibis Reader, and while of course I’ll miss his contribution at O’Reilly, I understand and support his decision. He joins an impressive list of O’Reilly alumni who are doing important and interesting work, and who remain very much a “FOO” (Friend of O’Reilly).

  6. andrew said:
    > while of course I’ll miss
    > his contribution at O’Reilly,
    > I understand and support his decision.
    with shortcovers pulling in
    i would think it would be
    very simple to “understand”
    a decision to go work on an
    e-book viewer/store app…


  7. andrew said:
    > My guess about PDF is that
    > most people are still reading these on PCs,
    > and in general PDF is a
    > much more familiar format than EPUB.

    my guess about .pdf popularity outrunning .epub
    is that most people are still reading these on pcs,
    and the desktop version of stanza is horrendous,
    and adobe digital editions is almost as bad…


    p.s. charles, i’m glad and impressed to hear that!

  8. Firstly, congrats on being elected to the board of the IDPF.

    The graph is pretty much just as I expected it to be. PDF a long way in front because it’s been the standard for so many years – people know it and are comfortable with it.

    EPUB is just starting to take traction, and with eReaders all the rage it shouldn’t take too long for the lines to meet.

  9. of course, people also hate .pdf.

    the reason people hate .pdf is
    because it’s a “frozen” format.

    so if the pagesize, for instance,
    doesn’t fit the view-port for the
    machine you are on, it’s ugly…

    or if the textsize is too small,
    the .pdf is unworkable for you.

    however, if you gave customers
    an e-book file-format that let
    them create their own .pdf files,
    customized to their view-port
    and their own preferred textsize
    — and font-choice and leading
    and background and so on —
    that might eclipse all the others.


    p.s. and yes, a light-markup
    file-format would fit this bill…

  10. As it relates to text books (which are far different than the latest from Brown, Patterson & King – what say you ? EPUB, is it enough ? Or will Textbooks be more like open source wiki like projects ?

    Why I ask ?




  11. There is nothing much fancy about this situation but your study would help to see that more people would love to change what they have or what they are working with. The users often change when they have a better product, that is the nature PDF remained to be the better product when it was introduced but as with time more user friendly products come and they do get acceptance with the users. For doing perfect Multivariate Testing things like this should also come into our consideration. The users would often change when they get better products for their needs. Most commonly used platform for EBooks would be PDF and it would take much more time for users to switch to EPUB.

  12. abandoning our little blog here to the spammers, are we?


  13. I am using PDF and will use it.
    I am sure no ePUB can over rank PDF. Adobe is great product company and it will remain.

    • I will not be so sure. MIcrosoft Windwos versions come with an antidote to that it’s called .xps.

  14. Bonus, I’m agree. Only PDF like a typical book product.

    DJVU – bad, EPUB, MOBI very bad.

    PDF for life.

  15. So much information into one single post. I really need to get a good look at this. Thanks a lot for posting.

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