Ebook Format Guide

Choosing an ebook format can feel like a technical chore, but it mostly comes down to one question: how will your readers use the book? A novel read on a phone has different needs from a cookbook with precise page layouts. In this ebook format guide, we’ll look at the main options, what each one does well, and how to choose without getting lost in file extensions.

For most text-based books, EPUB is the best place to start. It’s widely supported by ebook retailers and reading apps, and its reflowable text adjusts to the reader’s screen size and preferences. Readers can often change the font, text size, spacing, and background color, which makes EPUB a flexible choice for novels, memoirs, and nonfiction. EPUB can also include images, links, and other interactive features, though complex layouts may not look identical on every device.

PDF is a better fit when the page itself matters. It preserves a fixed layout, so diagrams, worksheets, forms, and carefully arranged pages stay in position. That consistency is useful for a workbook, a visual portfolio, or a guide with detailed charts. The trade-off is that a PDF can be awkward to read on a small screen: readers may need to zoom in and scroll around rather than simply increase the text size. If your book is mostly long-form text, PDF may be less comfortable than a reflowable format.

Kindle books have their own ecosystem to consider. Kindle devices don’t generally open an EPUB file as-is, but Amazon can convert EPUB files submitted through its publishing tools or sent using Send to Kindle. Authors publishing through Kindle Direct Publishing can typically upload an EPUB for processing, while Amazon delivers a Kindle-ready version to readers. Older formats such as MOBI have become less central to current Kindle publishing, so it’s wise to check Amazon’s latest file requirements before preparing a release.

Some books need more than a standard reflowable layout. Children’s picture books, comics, and richly designed cookbooks may benefit from fixed-layout EPUB or another format supported by the intended store and devices. Fixed layouts can protect the visual design, but they may limit text resizing and can be less accessible. When possible, include accessibility features such as selectable text, meaningful image descriptions, clear navigation, and a logical reading order. Then test the book on more than one screen size—what looks polished on a laptop might feel cramped on a phone.

So, what’s the practical choice? Use EPUB for most books that are primarily text, PDF when preserving the page design is essential, and a fixed-layout option when visuals and precise placement are central to the experience. You may need to provide more than one version for different platforms. Before publishing, preview each file and read a few pages on an actual device. The right ebook format is the one that lets your content feel natural, readable, and reliable wherever your audience opens it.