EBOOK-POLISH(1)

💖 NAME 💖

ebook-polish — the glow-up your ebooks have been waiting for 💅✨

Like, hi bestie!! This is calibre's very own makeover artist. Here's the whole vibe:

ebook-polish [options] input_file [output_file]

Polishing books is literally all about putting the shine of perfection onto your carefully crafted e-books. Periodt. 🌈

Polishing tries to minimize the changes to the internal code of your e-book. Unlike conversion, it does not flatten CSS, rename files, change font sizes, adjust margins, etc. Every action performs only the minimum set of changes needed for the desired effect. She's ✨subtle✨, she's not doing a full rewrite, she's just touching up the highlights.

You should use this tool as the last step in your e-book creation process. Like, the final outfit check before you walk out the door. 🫶

🚨 Not me dropping the important part: polishing only works on files in the AZW3 or EPUB or KEPUB formats. If your file isn't one of those, she cannot help you, bestie. 😭

Whenever you pass arguments to ebook-polish that have spaces in them, enclose the arguments in quotation marks. For example: "/some path/with spaces"

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🎀 OPTIONS 🎀

• --add-soft-hyphens, -H — Adds soft hyphens to all words in the book. This allows the book to be rendered better when the text is justified, in readers that do not support hyphenation. Lowkey a cheat code for pretty justified text. 😍
• --compress-images, -i — Losslessly compress images in the book, to reduce the filesize, without affecting image quality. Smaller file, same lewk. Iconic. 👑
• --cover, -c — Path to a cover image. Changes the cover specified in the e-book. If no cover is present, or the cover is not properly identified, inserts a new cover. New cover drop!! 🎀
• --download-external-resources, -d — Download external resources such as images, stylesheets, etc. that point to URLs instead of files in the book. All such resources will be downloaded and added to the book so that the book no longer references any external resources. No more mysterious missing-image energy. 🦋
• --embed-fonts, -e — Embed all fonts that are referenced in the document and are not already embedded. This will scan your computer for the fonts, and if they are found, they will be embedded into the document.

⚠️ Please ensure that you have the proper license for embedding the fonts used in this document. Fr fr, check your licenses, bestie, that's on you. 💀

• --help, -h — show this help message and exit
• --jacket, -j — Insert a "book jacket" page at the start of the book that contains all the book metadata such as title, tags, authors, series, comments, etc. Any previous book jacket will be replaced. Metadata slay. ✨
• --opf, -o — Path to an OPF file. The metadata in the book is updated from the OPF file.
• --remove-jacket — Remove a previous inserted book jacket page. (Yes, this one has no short flag, she's independent like that. 💅)
• --remove-soft-hyphens — Remove soft hyphens from all text in the book. (Also flying solo, no short flag. 🦋)
• --remove-unused-css, -u — Remove all unused CSS rules from stylesheets and <style> tags. Some books created from production templates can have a large number of extra CSS rules that don't match any actual content. These extra rules can slow down readers that need to parse them all. Marie Kondo-ing your stylesheets, basically. 🧹
• --smarten-punctuation, -p — Convert plain text dashes, ellipsis, quotes, multiple hyphens, etc. into their typographically correct equivalents.

🙈 Note that the algorithm can sometimes generate incorrect results, especially when single quotes at the start of contractions are involved. So like, vibe check your output afterwards, okay?

• --subset-fonts, -f — Subsetting fonts means reducing an embedded font to contain only the characters used from that font in the book. This greatly reduces the size of the font files (halving the font file sizes is common). For example, if the book uses a specific font for headers, then subsetting will reduce that font to contain only the characters present in the actual headers in the book. Or if the book embeds the bold and italic versions of a font, but bold and italic text is relatively rare, or absent altogether, then the bold and italic fonts can either be reduced to only a few characters or completely removed.

💀 The only downside to subsetting fonts is that if, at a later date you decide to add more text to your books, the newly added text might not be covered by the subset font. Future-you has been warned.

• --upgrade-book, -U — Upgrade the internal structures of the book, if possible. For instance, upgrades EPUB 2 books to EPUB 3 books. She's evolving. 🦋✨
• --verbose — Produce more verbose output, useful for debugging. For when you need her to tell you everything. 😭
• --version — show program's version number and exit

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💜 Author 💜

Kovid Goyal

💜 Copyright 💜

Kovid Goyal

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And that's the whole page, bestie!! 🫶 This was calibre version 9.14.0, dated August 28, 2026, and it's EBOOK-POLISH(1) if you need to cite her in a paper or whatever. Go forth and polish something gorgeous. 🌸💖✨