What is .epub?
.epub (Electronic Publication) is an open, reflowable e-book format based on web standards. EPUB files bundle HTML, CSS, images, fonts, and metadata into a compressed container, allowing text to adapt to different screen sizes and reading preferences.
This quick guide explains when to use .epub files, how to open them on any device, and how to share them instantly with FileXhost.
When to use .epub files
- You are publishing digital books, manuals, or long-form reading content.
- You want reflowable text that adapts to phones, tablets, and e-readers.
- You need features like adjustable fonts, themes, and built-in bookmarking.
- You plan to distribute content through e-book stores or reading apps.
How to open .epub files
EPUB files can be opened with dedicated e-reading apps like Apple Books, Google Play Books, Kobo, and many third-party readers on Windows, macOS, Linux, iOS, and Android. Desktop apps like Calibre or Thorium Reader also support EPUB. You can upload .epub files to FileXhost to host and share them as downloadable reading files.
Algorithm details
EPUB is a container format defined by the EPUB specification from the W3C. Internally, an EPUB file is a ZIP archive that contains XHTML or HTML5 content documents, CSS stylesheets, images, fonts, and a package document (content.opf) that describes the book's structure and metadata. A manifest and spine define which files belong to the book and in what reading order.
Browser & platform support
- Desktop: Not directly rendered by browsers, but readable via extensions and web readers that unpack the EPUB and display its HTML content.
- Mobile: Widely supported through built-in or downloadable reading apps on iOS and Android.
- OS: Supported on all major operating systems via e-reader apps like Calibre, Thorium, and vendor-specific software.
Format comparison
| Feature | Details |
|---|---|
| Layout | Reflowable by default, letting readers change font size and layout; unlike PDF, which uses fixed pages. |
| Compatibility | Widely supported across non-Kindle e-readers and apps; Kindle devices often require conversion to MOBI or AZW3. |
| Accessibility | Built on HTML/CSS, making it easier to support screen readers and accessibility features when authored correctly. |
| File Size | Generally smaller than equivalent PDFs, thanks to compressed HTML and images. |
How to create epub files
- Authoring Tools: Scrivener, Vellum, Atticus, Reedsy Book Editor.
- Desktop Software: Calibre, Sigil, Adobe InDesign (Export to EPUB).
- Converters: Pandoc, online converters that turn DOCX, Markdown, or PDF into EPUB.
- Programming: Custom scripts that generate EPUB from HTML/Markdown using libraries.
How to convert epub files
- FileXhost: Upload EPUB files to host and share them as download links.
- Calibre: Convert between EPUB, MOBI, AZW3, PDF, and many other formats.
- Online Tools: CloudConvert, Zamzar, and other web-based e-book converters.
- CLI: Pandoc or custom scripts to generate EPUB from Markdown, LaTeX, or HTML.
Advantages & disadvantages
Advantages
- Open, vendor-neutral standard based on web technologies
- Reflowable layout that adapts to any screen size
- Supports rich formatting, images, and embedded fonts
- Generally smaller and more comfortable to read than PDFs on mobile
Disadvantages
- Not natively viewable in standard web browsers without a reader
- Kindle devices prefer proprietary formats (MOBI/AZW3), requiring conversion
- Layout-sensitive documents (e.g., complex textbooks, comics) can be harder to design in EPUB
Tools & software
Readers
Apple Books, Google Play Books, Kobo, Thorium Reader, FBReader
Managers
Calibre, BookFusion, Kindle for desktop (with conversion)
Editors
Sigil, Scrivener, Vellum, Atticus
Frequently asked questions
Is EPUB better than PDF for e-books?
For reading on phones, tablets, and e-readers, EPUB is usually better because the text reflows and lets readers adjust fonts and layout. PDF is better when you must preserve an exact page layout, like for print-ready documents.
Can I read EPUB files on a Kindle?
Traditional Kindle devices do not read EPUB directly, but you can convert EPUB to Kindle formats (MOBI or AZW3) using Calibre or send-to-Kindle tools. Newer Kindle services also accept EPUB uploads and convert them automatically.
How do I create an EPUB from a Word or Markdown document?
You can use tools like Calibre, Pandoc, Scrivener, or Reedsy. Export your document to DOCX, HTML, or Markdown, then convert or export it as EPUB.
Are EPUB files DRM-protected?
The EPUB format itself does not require DRM, but many stores add DRM layers on top. DRM-free EPUBs are easy to move between devices; DRM-locked files may require specific apps or accounts.
Technical specs
- File type
- Ebook
- Extension
- .epub
- MIME type
- application/epub+zip
- Compression
- Lossless
- Max file size on FileXhost
- Up to 25 MB per file on the free plan and up to 1 GB on Pro FileXhost accounts.
Share .epub files instantly
Upload your .epub file to FileXhost to get a clean, shareable URL in seconds. View the file in a modern browser, protect access with optional settings, and let others download it without any confusing ads or cluttered file pages.
Upload .epub file