1) Download the kindlegen app zip file to your desktop. You can find it here:
Kindlegen file from official Amazon site
2) Open your C drive directory.
You’ll see other folders in there such as Program Files, Users, Windows etc. Make a new folder in this directory and rename it KindleGen.
3) Go back to the zip file on your desktop and double click to open it. Extract the contents in C:\KindleGen\
4) Make another folder inside C:\KindleGen\ folder named Book
5) So now you have a KindleGen folder on your C drive and inside there is a Book folder. Find an HTML, ePub, or OPF file that you wish to convert into a Mobi book and paste it into that Book folder.
6) Open Command Prompt (no need to open it as administrator).
7) Copy the following codes and paste in Command Prompt in. Make sure to change “your_book” to whatever the name of the file is you have in the Book folder along with the correct suffix (epub, opf, or html):
8) Hit the Enter button on your keyboard. KindleGen will convert the book and place the new Mobi file inside the Book folder.
9) KindleGen will use the standard c1 compression unless you tell it otherwise. The other choices are c0 (no compression) or c2 (the most compression.) To use c0 or c2, paste in one of the following:
C:\KindleGen\kindlegen.exe -c0 C:\KindleGen\Book\your_book.epub
C:\KindleGen\kindlegen.exe -c2 C:\KindleGen\Book\your_book.epub
10) Type below code in command prompt for some extra options to use: