[eschwartz]

Calibre Conversion -- Sticky: Read this before Posting PDF Questions

Originally Posted by Idolse

PDF format is the worst choice of source formats to use with Calibre, and conversions can range from decent to quite awful. Read here for the official statement on Calibre's PDF support.

This post will go into a little more detail on the various issues surrounding pdf conversions and what can be done about it. Note if your PDF looks like complete garbage after conversion (i.e. nothing at all like the original text) there is nothing to be done about it using Calibre.

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My PDF has a table of contents or links/bookmarks, but they weren't used during conversion

Calibre doesn't support the existing Table of Contents/links/bookmarks in a pdf, for either building a TOC or detecting chapters. Instead it uses a heuristic approach to guess where the appropriate chapter breaks are. This works well in some documents, but can produce poor results or false positives in other documents.

MobiPocket Creator is often suggested as a converter that handles PDF better than most others in many cases, but YMMV. There is simply no guarantee that PDF can be turned into something usable.