Why reflow matters
The defining feature of EPUB is that it does not have pages in the printed sense. The book is a sequence of XHTML documents, and the reading application decides where lines and pages break based on your screen, your chosen font and your preferred text size. Bump the type up two sizes on a phone and the words simply reflow to fit; do the same with a PDF and you are left pinching and panning across a frozen A4 layout. This is the single biggest reason e-readers favour EPUB: it treats a book as text to be presented, not as an image of a page.
What EPUB 3 added
EPUB 3 modernised the format by aligning it with HTML5 and CSS3, which brought richer typography, embedded fonts, audio and video, and meaningful support for accessibility and right-to-left scripts. A navigation document provides the table of contents, and a manifest lists every resource the book contains so nothing goes missing. Metadata — title, author, language, identifiers — is held in a package file, making EPUBs easy to catalogue. The catch is that capabilities vary between reading apps, so an advanced feature that shines in one reader may be quietly ignored in another.
Strengths
- Text reflows to any screen, so the book stays comfortable to read on phones, tablets and dedicated e-readers.
- Built on open web technologies, which makes the content inspectable and convertible.
- Supports embedded fonts, images, accessibility metadata and multiple languages.
- Widely supported across Apple Books, Google Play Books, Kobo and most open readers.
Limitations
- Amazon Kindle historically preferred its own formats, so EPUB has not always opened natively there.
- DRM-locked purchases are encrypted and cannot be freely opened or converted.
- Complex layouts such as illustrated cookbooks or comics reflow poorly compared with fixed pages.
- Rendering differs between apps, so the author’s exact styling is never guaranteed.
When to use EPUB
Choose EPUB for prose-led books — novels, essays, manuals — that readers will consume on varied devices and want to resize freely.
EPUB FAQ
- Is EPUB or PDF better for e-readers?
- EPUB is usually better because the text reflows to fit the screen and font size, whereas a PDF keeps a fixed page that you must zoom and scroll. PDF only wins when exact layout — forms, diagrams, print parity — is essential.
- Can Kindle read EPUB?
- Modern Kindle software and the Send to Kindle service now accept EPUB and convert it internally, but older devices expected Amazon’s own formats. For most books you can simply send the EPUB and let Amazon convert it; converting it yourself first is only worth doing when you want tighter control over the result.
- Can Morphr convert a book I bought?
- Only if it is DRM-free. Morphr converts EPUB to and from PDF, TXT, Markdown, HTML and DOCX in your browser, but encrypted shop purchases are locked by design and cannot be opened.