Last summer, Kobo Writing Life launched its professional EPUB conversion service on the Author Services tab of the Dashboard. Since then, we’ve seen one question come up a lot: what’s the difference between epub and epub fixed layout?

So here’s a short guide to determining whether your book is one or the other.

An EPUB, as you may already know, is just an eBook. There are two file formats for eBooks: EPUB and MOBI. EPUB is the global standard used in most e-reading devices (Nook, iBooks, Google and Kobo all use this format).

It’s important to note that in most cases where we say “epub”, we’re likely referring to a reflowable EPUB.

Reflowable EPUBs

This is a file where the text flows between pages, adjustable for font size, and thus not restricted to a specific page count. Increasing font size on your e-reader means the book’s page count will increase as it takes up more pages.

Reflowable EPUBs can therefore not have any header or footer elements other than those automatically inserted by the e-reader. There is no such thing as a “page” in a reflowable book. You are simply seeing one chunk of the never-ending flow of text.

Books that are usually reflowable: the average novel or memoir, books with minimal design elements and more text.

Fixed-Layout (FXL) EPUBs

A fixed-layout epub is a book where the text does not flow. Rather, it behaves like the text in a physical book: everything on the page remains fixed in place, and text cannot be enlarged. Each element of the page is coded firmly into place with HTML and CSS.

Books that are usually fixed-layout: A children’s picture book, a cookbook, a textbook with many sidebars and other graphical elements, heavily interactive books

Image-Based Fixed-Layout EPUBs

This is a subcategory of fixed-layout EPUB specially reserved for those books that are almost all image/graphical elements and little to no body text. The key difference between this and non-image-based FXL ebooks is that the elements of each page here are not coded in HTML; rather, each page in the book is recreated as one image (hence “image-based”). The images are then displayed to the user like regular pages, and the user can usually tap and zoom into them.

Books that are usually image-based fixed-layout: comic books, heavily illustrated children’s books (e.g. with stylized text that would be tricky to code properly into position)

When you send us a title for conversion through the Author Services tab on the KWL Dashboard, we will always assess the source file, and will recommend the right type of epub if we believe there may be an issue with the type of epub you chose in your order.