EPUB Tools

Transform EPUB to and from numerous formats

About EPUB

EPUB constitutes a reflowable eBook format that adjusts to different screen sizes and reading preferences.

Common Uses

Publishing digital books for e-readers
Creating responsive files for mobile reading
Distributing digital publications

EPUB Transformation FAQ

What is an EPUB ebook file?

EPUB is an open ebook format. The file is essentially a zipped collection of HTML pages, CSS, and embedded images, which means most reader apps and devices can open EPUB without conversion. An EPUB is a ZIP archive of XHTML and CSS with a manifest — essentially a small website packaged as a book. EPUB reflows text to any screen size and any font size, which is what makes it readable on a phone as well as an e-reader.

Why does the same EPUB book look different on two devices?

Because it is meant to. An EPUB is a package of structured text and styling that the reader lays out at your chosen font and size, so page count and line breaks are properties of the device, not of the book. Converting to a fixed-layout format freezes one particular rendering — good for printing, worse for reading on a phone. EPUB is the open ebook standard from the International Digital Publishing Forum, now maintained by the W3C.

Why do most bookshops hand out EPUB?

Because it is the open standard everything except Kindle settled on, so one file serves a Kobo, a phone, a tablet and a desktop reader alike. The format itself carries no lock of any kind. What a shop may add on top is a separate encryption layer tied to your account — that is the shop's wrapper rather than part of the format, and it is the whole difference between a file that converts here in seconds and one no converter can open at all.

Why does my purchased EPUB refuse to convert?

Because it is encrypted. A store-bought EPUB is locked to an account, and the file a converter sees is ciphertext rather than a book — there is nothing to read until the store's software decrypts it for its own reader. Removing that protection is a legal grey area in many countries and is not something this site does. Files you made yourself, or downloaded DRM-free, convert normally. EPUB has no fixed pagination, so page numbers are meaningless, and complex layout — tables, equations, multi-column — degrades badly.

What if my EPUB is a scan rather than real text?

Then nothing downstream can read it until OCR has run. A scanned page is a picture of words: it looks fine, and searching, copying or converting to an editable document all come back empty. Optical character recognition adds a real text layer over the image, after which the words are selectable and the conversion produces an actual document instead of a wrapper around a photograph.

Does an EPUB have fixed pages?

No — content flows, and pages appear only when something decides on a page size. Change the font, the margins or the screen and the page numbering changes with it. That is why a page reference from an EPUB is unreliable, and why converting to a fixed-layout format is the step that makes page numbers mean something.

Who controls the EPUB format?

Nobody, and that is the point of it. The specification is public, anyone may implement it without asking or paying, and no company can change the terms later — which is why archives, standards bodies and public institutions specify formats like this one for anything that still has to open in twenty years. The trade is not compatibility, which is excellent; it is that there is no vendor to call when some tool implements the spec badly.

Can I convert a whole folder of EPUB files in one go?

Yes — drop them in together and they are queued as one job rather than converted one at a time, with the same settings applied across the batch and the results returned together. Free accounts run a couple concurrently; a paid plan lifts both the concurrency and the per-file size limit, which is what makes converting a large archive practical.

Why convert EPUB to another ebook format?

EPUB already has the widest non-Kindle reader support — Apple Books, Kobo and Google Play Books all open it directly. Convert EPUB to AZW3 to side-load onto a Kindle, or to MOBI for Kindle hardware old enough to predate KF8. Convert to PDF when you need a fixed-layout copy for printing.