Calibre 3.12.0 For Windows (32/64-bit) & Portable Free Download Calibre 3.12.0 For Windows (32/64-bit) & Portable Download is an entire digital book library administrator that lets you thoroughly compose your accumulation. With Calibre 3.12.0 For Windows you can change your books to various organizations, and after that synchronize with the more significant part of your gadgets.