Calibre Ebook Manager 9.12.0

Calibre converts a book into the format your reader will actually open.

That is the job most people install it for, and everything else it does sits on top of that.

Download Calibre 9.12.0 - free and open source, Windows, macOS and Linux.

Which Format Does Your Reader Need?

This is the whole question, and the answer is short.

• Kindle - EPUB or AZW3. Amazon's Send to Kindle service now accepts EPUB and converts it on their side, so EPUB is usually the simplest route.
• Kobo - EPUB. It is the native format and needs no conversion at all in most cases.
• Phone or tablet reading apps - EPUB, which every serious reading app on Android and iOS handles.
• Comics and manga - CBZ or CBR, which are just archives full of images, and Calibre can convert between them or into EPUB.
• Anything else - EPUB. If you are unsure, convert to EPUB and keep the original.

Calibre reads MOBI, AZW, AZW3, EPUB, FB2, LIT, PDB, PDF, RTF, TXT, DOCX, HTML, CBZ, CBR and a long tail of formats almost nobody uses any more.

Converting a Book, Step by Step

1. Drag the file into the Calibre window, or use Add books. It lands in your library with whatever metadata it carried.
2. Select the book and click Convert books.
3. Pick your Output format from the dropdown at the top right. EPUB unless you have a reason to choose otherwise.
4. Leave the settings alone the first time. The defaults are good, and the Look and feel and Page setup panels only matter when something comes out wrong.
5. Click OK. The job runs in the background, and the new format sits alongside the original rather than replacing it.

Both versions now live in your library. To get the file out, right-click the book, then Save to disk, or send it straight to a connected device.

Why Your PDF Conversion Looks Terrible

PDF is the one format that regularly disappoints, and it is worth understanding why before you blame the software.

A PDF describes fixed positions on a fixed page size. An EPUB describes flowing text that rearranges itself to fit any screen. Converting one to the other means guessing where paragraphs, columns and headings were meant to be, and the guess is often wrong.

Simple, text-only PDFs convert acceptably. Anything with two columns, sidebars, tables, footnotes or scanned pages will come out broken, and no setting fixes that reliably.

If the PDF is a scan rather than real text, there is nothing to convert at all, since the pages are images. Reading it as a PDF in Adobe Acrobat Reader or on a larger screen is the better answer.

What Calibre Cannot Do

It cannot convert books that carry DRM. Most titles bought from Amazon, Kobo, Google Play Books and similar stores are protected, and Calibre will refuse them or produce an unreadable file.

That is not a bug or a missing setting. DRM-protected purchases are licensed to the store's own apps and devices, and removing that protection is illegal in many countries regardless of the tool used.

Books you own without DRM convert fine: anything from Project Gutenberg, Standard Ebooks, Humble Bundle, most indie publishers, DRM-free storefronts, and files you made yourself.

The Rest of Calibre, Briefly

• Library management - covers, series, tags, ratings, custom columns and saved searches, with metadata and cover art downloaded automatically for most books.
• A built-in reader - decent enough for checking a conversion came out right, with bookmarks and highlights if you want to read on the desktop.
• An ebook editor - opens EPUB and AZW3 files down to the HTML and CSS, for fixing a broken chapter break or a typo without a full round trip.
• Content server - serves your library over your home network, so any phone or tablet browser can read from it without syncing anything.
• News fetching - turns news sites into ebooks on a schedule and delivers them to your reader, which is the feature almost nobody knows about.
• Device sync - connect a Kindle or Kobo over USB and Calibre handles the transfer, or email books to your Send to Kindle address.

Which Download to Take

• calibre-64bit-9.12.0.msi - the standard Windows installer, and the right choice for most people. There is no 32-bit build any more.
• calibre-portable-installer-9.12.0.exe - the portable build. Runs from a folder or a USB stick and keeps your library with it, which suits a work machine or a shared computer.
• calibre-9.12.0.dmg - macOS.

The 212 MB download surprises people for a program that handles text files. Calibre ships its own Python and Qt runtime rather than depending on what your system happens to have, which is also why it updates cleanly and rarely breaks.

Development is fast, with a new release most weeks, so expect update prompts often.

Who Should Look Elsewhere

If all you want is to read one file, you do not need a library manager.

For a single EPUB, this free online EPUB file viewer opens it in a browser tab with nothing to install and nothing to upload elsewhere.

Comic archives in CBZ or CBR are zipped images that many image viewers open directly, including XnView.

If the file is a PDF and you just want to read it, a PDF reader will always beat a conversion.

The tell that Calibre is the right tool: you have more than a handful of books, in more than one format, and more than one place to read them. Below that, it is a lot of program for one file.

Quick questions

Download Calibre 9.12.0 and see how it handles your library, or tell us how you got on if you have used it before.