
Unless additional steps are taken, these books will fail to convert in calibre with the error: "KFXError: This is an Amazon KFX book. Each book will appear in a separate subdirectory of the "My Kindle Content" folder with a file extension of ".azw". The Kindle for PC and Kindle for Mac programs use Amazon's KFX format for most books. There is also a new method (#6) using an old version of the Kindle for Android app described here. (Details in this thread.)This means that methods 1, 2, and 4 described below are no longer effective for those books. Still have to figure this out, hopefully without having to buy something.Important update: Amazon has made a change to their service so the books published since can no longer be downloaded using Kindle for PC or Mac versions prior to 1.39. KFX Input plugin can be installed from within Calibre.Configure with the Kindle serial number.
Digital content on Amazon > select the book > more actions > download and transfer via USB. Unfortunately since the introduction of KFX, it also means manually downloading Kindle ebooks from the Amazon website, and then importing into Calibre, and then sideloading into the Kindle device, as such: This consists of installing and configuring two plugins. Configuring Calibre to strip out encryption from Kindle ebooks Things are pretty solidly in favor of De-DRM these days, though on the Apple/OSX/iOS platform the use of Fairplay makes decryption very difficult. Over the years there was a back-and-forth of changing encryption and improved de-encryption tools. Therefore, there is a De-DRM plugin for Calibre which makes short work of the DRM. I realize the importance of DRM, but as a consumer it is unacceptable (if avoidable). Removing DRM from Kindle is important so that one has access to what one has purchased. It keeps a metadata file as well as a book cover image (if available) and then one file each for one or more filetypes (e.g., epub, pdf, azw, mobi, etc.). When renaming the author or title, the file folders are renamed as well. It organizes files in folders based on the author(s) name(s), and subfolders based on the title name. Calibre calls itself an ebook management tool, but really any digital document can be stored in it.