Tech 101: What Is an ePub?
By Hufsa Tahir
What is an ePub file?
An ePub file is the digital format of a book used across all eReading devices and apps (Kobo, Nook, Adobe Digital Editions, etc). Amazon devices and apps use a proprietary version of an ePub called a MOBI file.
When you upload a Word document to Kobo Writing Life, it is automatically converted to ePub format that can be read by multiple devices.
There are two kinds of ePubs: reflowable and fixed-layout.
Reflowable ePub is the format used in the average novel. These are called reflowable because they are not bound by specific page numbering – the text flows across as many pages as it needs to. If you increase the font size of a reflowable ePub, there will be fewer words on your screen, and so the book will naturally have more pages.
Fixed-Layout ePub is exactly what it sounds like. The book is static, like a PDF file. Everything is set into a specific position: text, images, audio, etc. Nothing moves, and text cannot be resized, so these ePub files can have page numbering in the header or footer. An illustrated children’s book, for example.
Think of reflowable ePubs like water, flowing to fit the space they are given. Fixed-layout ePubs are like ice, unchanging.
Since most books books that are published are novels, we’re going to look at reflowable ePubs more closely.
Why a Reflowable ePub and not a PDF?
A reflowable ePub file can respond to user commands, like bigger font sizing, more margins on the sides, etc. It is reactive to user input, and will adjust its pages to suit. You can’t do this with a PDF. On many eInk readers, you can’t tap and zoom in on text, so a PDF with small font may be completely illegible.
Why a Reflowable ePub and not a Word Doc?
Doc and Docx are formats read only on word-processing software. They cannot be read by eReading devices and apps.
Word Doc versus Reflowable ePub
As mentioned before, when you upload a Word doc to KWL, it will be converted to an ePub so that any eReading device can display it. However, the Word doc is not a good indicator of what the ePub file will look like. Margins and spacing can appear very different in the ePub file.
There are key differences between the two that can cause errors in conversion. You can avoid these errors if you do not format your Word doc like a print version. Remember, an ePub is not identical to the print version, nor should it look as such.
Things to deal with in your Word Doc pre-upload:
- Page Numbers: Reflowable ePub files cannot have preset page numbers. The page count varies with font size, margin size, and a number of other factors that a reader can adjust. So if your Word document has page numbers, once you upload it and it converts to ePub, these numbers will be treated like lines of text, and it will end up appearing tacked onto a paragraph nearby.
- Header/footer text: Reflowable ePub files cannot have preset headers or footers. Having headers/footers in your Word document will similarly result in that text appearing tacked onto a paragraph near it.
- Manual hard returns: Hard returns occur when you press the Enter key. Hitting Enter to add extra space between paragraphs or to add spacing to push the next chapter to a new page can backfire. These hard returns will lead to huge blank spaces in your final converted file. Use page breaks instead.
- Margins and spacing: Your Word document’s margins and spacing (page margins, paragraph spacing, etc.) are not going to carry over well to the ePub. If anything, margins and spacing, like hard returns, may cause odd formatting errors. So avoid doing this to your Word doc (note the page numbers in the footer that shouldn’t be there):
- Image sizes: the size of an image in Word is not the size it will appear in an ePub opened on a device. The ePub relies on the resolution of the image (i.i. its height and width in pixels). So dragging and resizing an image in Word will not change its resolution. Resize the image first, and then insert it into your Word doc. You can use any photo editing program, including GIMP and Paint (both free).
Dealing with these key differences between a Word doc and an ePub will allow your doc to convert more smoothly, with less change of formatting errors.