Kindle HowTo: Change Margin
For simple adjustment of the left and right margins to one of the three preset values, use the "Words per Line" option on the font size page (press Aa key to the right of the spacebar on the keyboard). The option may be named "Words per Line" but what it really does is to alter the left and right margins.
- On your Kindle, go to the home page. NOTE: if the next steps are completed while an ebook is open, the change will not take effect.
- Connect your Kindle to your computer with a USB cable.
- Open the folder "system" in the root of the Kindle's internal storage memory. If you're on a Windows machine, this might be hidden from you. Be sure to set Folder Options to ‘Show hidden files, folders, and drives’ and uncheck the ‘Hide unprotected system files’ option. Alternatively, try typing in the system folder's address explicity, e.g. if the Kindle's drive letter is H, the address would be H:\system\
- Open the "com.amazon.ebook.booklet.reader" folder.
- Open the "reader.pref" file in a text editor. This is a plain text file with Unix line endings.
- There is a line in reader.pref that starts "HORIZONTAL_MARGIN=". Change the number (Default=40) that follows to the desired number. Margin-widths of 20, 15, and 10 are good starting points for determining what you're most comfortable with. I find that 0 (zero) puts the text too close to the bezel surrounding the display (particularly difficult on the eyes with graphite colored bezel).
- Save and close the file.
- Eject and disconnect the Kindle.
- Restart your Kindle (Menu/Settings/Menu/Restart)
Your default margins when reading books have now been changed. If you change the 'Words per Line' preference in the Font Size dialog, you will undo the change to the margins that you have just made.
Getting the reader.pref to not be overwritten can be a bit tricky. See this thread for tips and tricks