Convert MOBI to PDF

A format built for the first Kindle

MOBI descends from the Mobipocket format Amazon bought in 2005, and its age shows in what it can express. Underneath it is essentially HTML 3.2 from 1997 with a compressed index wrapped around it — so a MOBI has no real stylesheet, limited control over fonts and spacing, no proper tables, and none of the typographic capability a modern e-book format has. Converting one to PDF therefore produces something plain, and that plainness was in the book rather than introduced by the conversion.

Many .mobi files are in fact two books in one container. When Amazon moved to the newer AZW3, it shipped dual-format files carrying both the old and the new version so that older Kindles would still work. The better version is used where one is present, which is why the same book can convert noticeably better than its extension suggests.

What comes across is the text in chapter order, the pictures, and the structure the book declares: a table of contents becomes the PDF's bookmark sidebar, and internal references become working links. Text stays real text, so the result is searchable and quotable. As with any e-book, the conversion is committing a reflowable book to fixed pages — the page numbers correspond to nothing in any other edition, and nobody can make the text bigger afterwards.

DRM cannot be removed and KFX cannot be read. A book bought from the Kindle store is usually encrypted to an account, and no converter can open it — not this one and not any other, whatever it claims. KFX, Amazon's current format, is a separate matter again and is not handled here. Books from Project Gutenberg, Standard Ebooks, direct purchases and anything you made yourself carry no DRM and convert normally. If our server is unreachable, the page says so and converts locally, keeping chapters, text and pictures but not the links or the outline.

When you want something else

Calibre is the right tool for anything beyond a single file, and it is free. ebook-convert book.mobi book.pdf --pdf-page-size a4 is the command line behind it, and the interface gives you control over margins, font size, headers and the table of contents that a one-click conversion cannot. It also converts between every e-book format there is, which matters if what you actually want is an EPUB.

And that is usually the better destination. Converting a MOBI to EPUB rather than PDF keeps the book reflowable, so it stays comfortable to read on a phone or an e-reader — where a fixed A4 page means pinching and panning on every page. Convert to PDF when the book has to be printed or annotated on paper, and to EPUB when it has to be read.