Kindle’s ebook formats

May 21, 2009

12.7.12 This page is probably out of date, as I haven’t updated it since the kindle 2. I mean, what I said about .mobi being the same thing as .azw still stands, but I can’t vouch for anything else.

I don’t know how many Kindle owners drop by here, but more should, because reading public domain books has just gotten even easier.

Amazon keeps pretty quiet about what formats the Kindle does and doesn’t support. Here’s what you need to know: the proprietary Amazon format, .azw, is exactly the same thing as a Mobipocket book, (.mobi). The Kindle also natively supports plain text files.

Project Gutenberg has always had all of its books avalable as .txt files, and you can move those straight to your Kindle via USB. Recently, though, they’ve been making their books available in the .mobi and .epub (for Sony Reader) formats, which means that you can get the books with more formatting and, sometimes, illustrations. Mobipocket files, like text files, can be transferred straight to your Kindle with no reformatting.

The Kindle DX, which is available for preorder now, will natively support .pdf documents as well, which means that you will be able to transfer any book from the Internet Archive or Google Books straight to your Kindle without reformatting. I’ve been trying to come up with ways to justify ordering one, but my Kindle is less than a year old, so I don’t think it’s going to happen.

ETA: The Kindle 2–that’s the regular one–now supports pdf natively. I mean, I haven’t tried it out, but that’s what I’m told.


  1. From my understanding the Kindle format is actually a modified mobipocket format but basically you should be able to read any non DRM (digital rights managment) mobipocket book with a simple name change for the format. Your Kindle might even read it directly without any name change. For books that have DRM attached, there is some sort of flag attached that only unlocks for a specific reader even it is exactly the same file.

    The Kindle DX does get a lot of my interest but it may be a bit too large physically for take everywhere use like my Palm TX PDA. The built in .pdf format is quite tempting though especially now that basically the entire Bodleian Library is being digitized, almost all of which is now public domain time wise. It’s also being priced rather high even if it offers a higher resolution screen and better internet connectivity.

    I’m not a fan of .pdf format though since it is a memory hog and really slows down a web browser if read through that method. It isn’t too bad if you use the stand alone reader by itself. Basically if I have to read a pdf file on the web, I download it and open with the standalone reader.

    There are more ebook readers coming soon that have a similar free connection to the internet like the Kindle that support similar formats. One that I am keeping my eye on is a $199 5″ BeBook reader that has a SD card slot and also a $30 wireless SD card so that combo might also offer free wireless. The size is acceptable for everywhere use and it supports a ton of formats including mobi, txt, epub and pdf. Supposedly it is coming in September. I may end up waiting until this fall before getting any kind of e-ink reader.

    Since you already have a Kindle, it’s probably best to wait for a second generation color version in probably 2 or 3 years. You should have higher resolution and worked out bugs for a color display by then. For .pdf files that are intended for larger format displays you really do want higher resolution since it can be difficult to format for lower resolution displays if you have a lot of photos/illustrations and such as part of the file.

  2. Kindles do read .mobi without any name change or conversion.

    I;m really happy with my Kindle 1 — I don’t care about lack of color, or low resolution, or that there’s only four different shades of gray. As long as I can read it as easily as a page in a book, I’m fine. If I wanted to be looking at illustrations, I would use a real book, or my computer screen. Pdf support is the one thing I really want and haven’t got.

    So, I’m not going to get a DX. It’s expensive, and it’s on the large side. But I will continue to covet it.

  3. I am enjoying my Kindle 2, having just finished Little Women for the first time, a very fine book.

    A DX seems a bit too big for me, and too expensive. I’m sure that many amazing things are in store for ebooks readers in the next few years.

  4. Kindle Wireless can switch back and forth between reading and listening, and your spot is automatically saved. Pages automatically turn while the content is being read, so you can listen hands-free. You can choose from both male and female voices which can be sped up or slowed down to suit your preference. In the middle of a great book or article but have to jump in the car? Simply turn on Text-to-Speech and listen on the go.

    • And somehow none of those features are as cool as the scroll wheel you got rid of with the 2nd gen Kindle. Oh well.

  5. You say that a Kindle could read .mobi Can other readers that are .mobi compatible read the Kindle format .azw or does the DRM get in the way?

    • Sadly, nothing else can read the .azw format.

  6. Mobipocket .prc books opened in Kindle on my ipod touch…! No problem in it.

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