# 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.

- Canonical page: https://kdp123.com/t/calibre/
- Official site: https://calibre-ebook.com
- Categories: Writing & Formatting
- 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
- Official Amazon product: No
- 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.

## 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](https://kdp123.com/t/sigil/)
- [Pandoc](https://kdp123.com/t/pandoc/)
- [Jutoh](https://kdp123.com/t/jutoh/)
- [Draft2Digital](https://kdp123.com/t/draft2digital/)

## Sources

- https://calibre-ebook.com/about
- https://github.com/kovidgoyal/calibre