Ebook typography has evolved significantly since the early days of digital publishing. While readers once had no choice but system fonts, modern ebook formats support embedded custom fonts that travel with the publication. This allows publishers to maintain brand identity and ensure designed reading experiences across devices.
However, ebook font embedding comes with unique challenges. File size is critical—ebook distribution platforms often have size limits, and large files affect download times and storage on reader devices. Additionally, many readers override publisher fonts with their personal preferences, meaning your custom typography may not be seen by all readers.
This guide covers font formats for major ebook platforms, explains embedding and subsetting techniques, and helps you make informed decisions about when custom fonts add value to your digital publications.
Ebook Format Font Support
Different ebook formats have different font capabilities. Understanding these differences helps you prepare fonts correctly for each distribution channel.
Font Support by Format
EPUB 3 (Industry Standard)
Supports OTF, TTF, and WOFF fonts. Fonts are embedded in the EPUB package and referenced via CSS @font-face. Most ereaders (Kobo, Apple Books, Google Play Books) render embedded fonts correctly.
Kindle (KF8/AZW3)
Amazon converts EPUBs to their proprietary format. Custom fonts may or may not survive conversion. Many Kindle users set preferred fonts in device settings, overriding publisher fonts. Test thoroughly on actual Kindle devices.
PDF (Fixed Layout)
Full font support with embedding. Works well for design-heavy publications (art books, magazines) but lacks reflowable text. See our print designers guide for PDF font details.
Font Subsetting for Ebooks
Full font files can add 200-400KB per weight to your ebook. With Regular, Italic, Bold, and Bold Italic, you're looking at nearly 1MB just in fonts—potentially doubling your ebook's file size. Font subsetting removes unused characters to dramatically reduce file size.
Subsetting Strategy for Ebooks
English-Only Publication
- • Latin Basic + Extended subset
- • Include common punctuation
- • Add currency symbols if needed
- • ~60-70% size reduction
Multilingual Publication
- • Include all required scripts
- • Consider separate font files per language
- • Balance coverage vs. file size
- • May need full character sets
Use our font subsetter tool to create optimized font files for your ebooks. For guidance on specific languages, see our guides on Chinese, Japanese, and Arabic font subsetting.
Embedding Fonts in EPUB
EPUB files are essentially ZIP archives containing HTML, CSS, and resources including fonts. Embedding fonts requires placing the font files in your EPUB structure and referencing them in CSS.
/* EPUB CSS - Font embedding */
@font-face {
font-family: 'BookFont';
src: url('../fonts/bookfont-regular.otf');
font-weight: normal;
font-style: normal;
}
@font-face {
font-family: 'BookFont';
src: url('../fonts/bookfont-italic.otf');
font-weight: normal;
font-style: italic;
}
@font-face {
font-family: 'BookFont';
src: url('../fonts/bookfont-bold.otf');
font-weight: bold;
font-style: normal;
}
body {
font-family: 'BookFont', Georgia, serif;
}EPUB File Structure
Place fonts in a /fonts/ or /OEBPS/fonts/ directory. List them in your content.opf manifest with the correct media-type (application/vnd.ms-opentype for OTF, application/font-woff for WOFF).
Font Licensing for Ebooks
Ebook font embedding is a distinct license category. Desktop, web, and app licenses typically don't cover ebook distribution. When purchasing fonts for ebook use, look specifically for "ebook" or "digital publishing" licenses.
Licensing Considerations
Ebook licenses are often priced per title or per distribution volume. Some foundries offer unlimited ebook embedding as part of their web font license. Always verify embedding rights before including fonts in distributed ebooks. See our font licensing guide for details.
Open-source fonts like Google Fonts (licensed under OFL) are safe for ebook embedding without additional licensing costs. This makes them excellent choices for publishers seeking quality typography without licensing complexity.
Conversion Workflow for EBook Fonts
Verify Ebook Embedding Rights
Confirm your license covers ebook distribution. Obtain appropriate license if needed.
Convert to EPUB-Compatible Format
Convert fonts to OTF or TTF using our WOFF2 to OTF or WOFF2 to TTF converters.
Subset for Required Characters
Use our font subsetter to include only the characters your ebook uses.
Test on Multiple Devices
Preview your ebook on various readers (Kindle, Kobo, Apple Books, Google Play Books) to verify font rendering.
Tools and Resources
WOFF2 to OTF Converter
Convert web fonts for EPUB embedding
Font Subsetter
Reduce font file size for smaller ebooks
Font Licensing Guide
Understand ebook embedding rights
Font Subsetting Guide
Learn advanced subsetting techniques
External Resources
- EPUB 3 Specification - Official W3C EPUB standard
- Kindle Direct Publishing Font Guidelines - Amazon's font documentation
Written & Verified by
Sarah Mitchell
Product Designer, Font Specialist
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