EPUB is the open ebook standard maintained by the W3C (formerly the IDPF). Version 2 appeared in 2007 and EPUB 3, based on HTML5 and CSS, is the current version.
An EPUB file is a ZIP archive of XHTML content, CSS, images, fonts and metadata. Its text is reflowable, adapting to any screen size and font setting, while EPUB 3 also supports fixed layouts, audio, video and accessibility features. Apple Books, Kobo, Google Play Books and most library apps use EPUB, and Kindle accepts EPUB through Send to Kindle.
| Extension | .epub |
|---|---|
| Full name | Electronic Publication |
| Type | E-books |
| Typical size | 300 KB–5 MB per book; larger for illustrated books |
How to open a .epub file
| Device | How to open it |
|---|---|
| Windows | Free apps like Calibre, Thorium Reader or Kobo Desktop open EPUB. |
| Mac | Apple Books opens EPUB natively. |
| iPhone / iPad | Apple Books opens EPUB natively. |
| Android | Google Play Books, Kobo and Lithium open EPUB. |
| Linux | Calibre, Foliate and Thorium Reader open EPUB. |
Converting .epub files
Calibre converts EPUB to PDF, AZW3 or MOBI and vice versa. For Kindle devices, Amazon's Send to Kindle service accepts EPUB directly and converts it for you.
How to send a .epub file
- Open sendryo.com on the device that has the file and add it.
- Tap Get share code.
- On the other device, enter the code — the .epub file arrives directly, unchanged, at full quality.
Tips for sharing .epub files
- Store-bought EPUBs are usually DRM-protected and tied to the buyer's account, so they will not open for someone else.
- To get an EPUB onto a Kindle, use Send to Kindle (email or app) rather than copying the file directly over USB.
- On iPhone, open the received EPUB with Apple Books from the share sheet so it is added to your library.
More: how to send ebooks (epub and mobi).
Frequently asked questions
Can Kindle read EPUB files?
Kindle devices cannot open EPUB files copied directly, but Amazon's Send to Kindle service accepts EPUB and converts it automatically. Use the Send to Kindle app, website or your Kindle email address. Calibre can also convert EPUB to AZW3 for USB transfer.
What is the difference between EPUB and PDF?
EPUB is reflowable, so text adapts to screen size and font settings, which is ideal for phones and e-readers. PDF has a fixed page layout that looks the same everywhere, better for printed documents, forms and complex designs, but harder to read on small screens.
How do I open an EPUB on Windows?
Windows does not include an EPUB reader. Install a free app such as Calibre, Thorium Reader or Kobo Desktop. Some browsers also support EPUB through extensions.
How do I send a large .epub file?
Open Sendryo on both devices, add the .epub file and share the 6-digit code. It goes directly to the other device at original quality, with no size limit set by us and no upload to a server.