The Kindle is a great reading device, but its font selection isn't great. If you've been struggling to find a font that works for you, How-To Geek has put together a guide to jailbreak and install custom fonts on any generation of Kindle.
The steps for both jailbreaking your Kindle and installing the new fonts are fairly simple, and you'll find guides for both on How-To Geek. The end result is that you can customise your Kindle with any TrueType font you want so you can read comfortably. Head over to How-To Geek for all the instructions. The whole process shouldn't take more than 20 minutes, and don't forget you can do the same thing on Android.
Hack Your Kindle for Easy Font Customization [How-To Geek]