The Amazon Kindle is a great ebook reader, but it's tightly tied to Amazon's ecosystem. If you have a Fire tablet or a smartphone, you can download other e-reading apps to beef up your library, but with the E Ink Kindles (including the Paperwhite and Oasis) you're pretty much tied to getting your content directly from Amazon.
Well, sort of. Using a bit of free software, you can take ebooks in the EPUB, Mobi, and PDF formats and zap them over to your Kindle lickety-split. Here's how to do it.
Find Your Kindle Email
The easiest way to put books on your Kindle is to do it via email. To get your Kindle's email address, go to amazon.com/myk using your PC's web browser. Up top, click the Devices tab. In the list below, find the relevant Kindle device and click the three dots on the left. In the pop-up window, you'll see an @kindle.com email address. (It's set to a default address, but you can change it by clicking Edit.)
Back up top, click the Preferences tab and scroll down to Personal Document Settings. Click the down arrow on the right and scroll to Approved Personal Document E-mail List. The email attached to your Amazon account should be listed here. If that's the email address you'll be using to send e-books to your Kindle, you're all set. To use a different email, click Add a new approved e-mail address and enter the address you want to use.
Remember, your Kindle needs to be attached to a Wi-Fi or 3G network for this to work. It doesn't have to be your home network, of course; you can go to a coffee shop or a public library, for instance.
Choose Your E-Book Format
Now you know how to email an e-book to your Kindle, the next step is to figure out your e-book's format, which will determine how best to send it.
Good news: If your books are in the Mobi format, they're already readable by the Kindle. Attach the file to an email, send it to your Kindle's email address (with any subject, and nothing in the body of the email), and it should appear on your Kindle shortly. You can also drag and drop the file onto your Kindle if you attach the device to your PC with a USB cable.
Amazon can automatically convert PDFs into the Kindle format, but you get two formatting choices. If you want your Kindle to display every page in the PDF as if it were a graphic, just email the .pdf file to your Kindle's address without a subject line.
That will maintain the formatting and graphics, but the font size may be too small to read. If you're okay with this kind of formatting, you can also drag and drop the file onto your Kindle if you attach the device to your PC with a USB cable.
Your other option is to attach the PDF file to an email, and make the subject line "Convert"—just that word. Send it to your Kindle email address and your PDF will be converted into a Mobi file, where you can control the font size and formatting. The graphics will still be in there as well, but you'll lose the layout of the original PDF.
EPUB is a common ebook format around the web, but the Kindle can't read it natively. That's okay; you can convert .epub files to Mobi files for the Kindle to read.
The key is a free piece of software called Calibre. Available for Windows and Macs, it can reformat almost any kind of ebook for most ebook readers, although cracking the copy protection on books purchased from Amazon or certain other stores is forbidden. When you set up the software, it asks you for your model of ebook reader, and a pop-up suggests sending the books by email. Fill in the email address for your Kindle and the authorized email address with which you've set to send documents to your Kindle.
Once you set up Calibre, click on Add Books and pick out any free ebook files you've downloaded. They'll appear in the Calibre library. Now click on an entry in your Calibre library and choose Convert Books from the top bar.
In the upper right-hand corner, make sure to set the Output Format to Mobi. Click OK, and wait until the Jobs number at the lower-right of the main screen goes from 1 down to 0. Now select the title again and click Save to Disk.
Pick the folder you want to save it in. It'll create a subfolder with the name of the author. In Explorer or Finder, drill into that folder until you find the Mobi file within, which you can email to your Kindle or drag and drop onto it using a USB cable.
Also, remember, text files, blog posts, Word documents, and more can be emailed to your Kindle, too. Just send them to your Kindle's email address and enjoy.