calibre
calibre is a free, open-source ebook manager for Windows, Mac and Linux that converts Word and other files to EPUB and includes an EPUB editor.
At a glance
- Price
- Free (Free and open source (GPL-3.0); funded by donations.)
- Platforms
- Windows, Mac, Linux
- Outputs KDP-ready files
- Yes
- Touches your KDP account
- No
- Categories
- Writing & Formatting
- Last checked
- 2026-11-09
Summary
calibre is mainly an ebook library manager, but its converter turns DOCX and many other formats into EPUB and its built-in editor lets you fix the HTML and CSS inside an EPUB or Kindle file. KDP publishers use it to make or repair an ebook file; check the result in Kindle Previewer before uploading. It is not a print layout tool, so it does not produce paperback interiors at KDP trim sizes.
Best for
- Converting a Word manuscript to EPUB or fixing an existing EPUB for free
Pros
- Free and runs on all three desktop systems
- Converts between dozens of ebook formats and can edit EPUB internals
Cons
- Ebook only; no print PDF layout
- Conversion output often needs manual cleanup for a polished book
Alternatives
- Sigil: Sigil is a free, open-source EPUB editor for Windows, Mac and Linux that lets you edit an ebook's HTML, CSS and structure directly.
- Pandoc: Pandoc is a free, open-source command-line converter that turns Markdown, Word and other formats into EPUB, DOCX and, through LaTeX, PDF.
- Jutoh: Jutoh is a desktop ebook editor for Windows, Mac and Linux that imports Word files and compiles EPUB and Kindle-ready books, sold for a one-time price.
- Draft2Digital: Draft2Digital is an ebook and print-on-demand distribution service for publishing wide that also formats Word manuscripts into EPUB and print PDF.
Sources
Facts on this page come from the vendor and these pages. Prices change; confirm on the vendor site.
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