.epub — Electronic Publication
The open ebook format used by many readers, stores, and publishing workflows.
About this format
EPUB packages HTML, CSS, images, metadata, and navigation into a zip-based ebook. It is designed for reflowable reading, though fixed-layout EPUB also exists.
Use EPUB for ebooks that should adapt to screen size. Use PDF when page fidelity matters more than reading comfort.
Real-world samples & file sizes
EPUB samples should be judged in the sizes people actually receive, upload, or export. These reference cards show the common shapes and settings to check before choosing a conversion target.
international page
The default document shape for many countries.
US page
Important for North American documents.
report
Checks navigation, thumbnails, and file size scaling.
image-heavy file
Useful when the format often stores scanned pages.
Reference dimensions are platform-style targets. Compatibility and format facts are verified from the linked online sources below.
Pros
- +Reflows across screen sizes
- +Open publishing standard
- +Good metadata and navigation support
Cons
- −Layout can vary by reader
- −DRM and store requirements differ
- −Complex books need testing on real devices
EPUB vs other formats
| vs | Size | Quality | Note |
|---|---|---|---|
| Usually smaller | Reflowable rather than fixed | EPUB is better for reading; PDF is better for exact pages. | |
| MOBI | Varies | Modern EPUB is more open | MOBI is older and Kindle-specific historically. |
Where it works
- iOS Books
- Android readers
- desktop reader apps
- Browsers need an EPUB reader app or JavaScript reader
- Apple Books
- Kobo
- Calibre
- Thorium Reader
- Google Play Books
Frequently asked questions
- Is EPUB better than PDF for books?
- For reading on phones and ereaders, usually yes. EPUB reflows text; PDF preserves fixed pages.
- Can browsers open EPUB directly?
- Not as a native media type in normal browsing. Use an EPUB reader or web app.
Sources
- W3C EPUB 3.3 - current EPUB core specification
- Library of Congress file format descriptions - archival format descriptions and sustainability notes