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What is an EPUB?

EPUB is the open standard file format for ebooks: a zipped package of the book's text, images and styles that a reading app reflows to fit any screen and type size. Chapbook exports EPUB 3, the current version of the standard.

What is inside one

An EPUB is a ZIP file with a fixed structure: the chapters as XHTML, a stylesheet, the images, the fonts if it carries any, and a package file that lists them in reading order with the book’s title, author and language. A navigation document gives reading apps the table of contents.

Because the text is not fixed to pages, the reading app lays it out on the fly. The reader picks the type size and the screen decides the line length, which is why an EPUB reads well on a phone where a PDF page would need zooming.

EPUB or PDF?

They do different jobs. A PDF is the book exactly as typeset, with the same pages everywhere, which suits a designed guide and anything meant to be printed. An EPUB gives up fixed pages for text that fits any screen, which suits reading apps and ebook stores.

Chapbook’s EPUB

On a paid plan, Chapbook exports every book as both. The EPUB 3 is reflowable, with a navigable table of contents, and the pipeline that builds it is validated against EPUBCheck, the standard’s own conformance checker. The sample on this page has its EPUB beside the PDF for download.

In a real book

Cover of The Pricing Playbook by Jane Founder: a brass balance scale lit from the left on deep teal above white type, subtitle “How founders set a price they can defend”.
Title page. Page 1 of The Pricing Playbook.
Copyright. Page 2 of The Pricing Playbook.
Contents. Page 3 of The Pricing Playbook.
Introduction. Page 4 of The Pricing Playbook.
Introduction. Page 5 of The Pricing Playbook.
Why Guessing Fails. Page 6 of The Pricing Playbook.
Why Guessing Fails. Page 7 of The Pricing Playbook.
Why Guessing Fails. Page 8 of The Pricing Playbook.
Why Guessing Fails. Page 9 of The Pricing Playbook.
What You Are Actually Selling. Page 10 of The Pricing Playbook.
What You Are Actually Selling. Page 11 of The Pricing Playbook.
What You Are Actually Selling. Page 12 of The Pricing Playbook.
What You Are Actually Selling. Page 13 of The Pricing Playbook.
Interview Ten Customers. Page 14 of The Pricing Playbook.
Interview Ten Customers. Page 15 of The Pricing Playbook.
Interview Ten Customers. Page 16 of The Pricing Playbook.
Interview Ten Customers. Page 17 of The Pricing Playbook.
Interview Ten Customers. Page 18 of The Pricing Playbook.
Choose the Value Metric. Page 19 of The Pricing Playbook.
Choose the Value Metric. Page 20 of The Pricing Playbook.
Choose the Value Metric. Page 21 of The Pricing Playbook.
Choose the Value Metric. Page 22 of The Pricing Playbook.
Draft Three Tiers. Page 23 of The Pricing Playbook.
Draft Three Tiers. Page 24 of The Pricing Playbook.
Draft Three Tiers. Page 25 of The Pricing Playbook.
Draft Three Tiers. Page 26 of The Pricing Playbook.
Set the Numbers. Page 27 of The Pricing Playbook.
Set the Numbers. Page 28 of The Pricing Playbook.
Set the Numbers. Page 29 of The Pricing Playbook.
Set the Numbers. Page 30 of The Pricing Playbook.
Say the Price Out Loud. Page 31 of The Pricing Playbook.
Say the Price Out Loud. Page 32 of The Pricing Playbook.
Say the Price Out Loud. Page 33 of The Pricing Playbook.
Say the Price Out Loud. Page 34 of The Pricing Playbook.
Revisit Every Quarter. Page 35 of The Pricing Playbook.
Revisit Every Quarter. Page 36 of The Pricing Playbook.
Revisit Every Quarter. Page 37 of The Pricing Playbook.
Revisit Every Quarter. Page 38 of The Pricing Playbook.
Conclusion. Page 39 of The Pricing Playbook.
Conclusion. Page 40 of The Pricing Playbook.
Appendix: The Interview Script. Page 41 of The Pricing Playbook.
Appendix: The Interview Script. Page 42 of The Pricing Playbook.
Back cover of The Pricing Playbook: the description over the cover's artwork.
Introduction 5 / 44
The Pricing Playbook, how founders set a price they can defend: a nonfiction book of 9,862 words and 43 pages on 6 × 9 in, generated from one brief and exported unedited. It is a sample, not a customer's book. Download the PDF (381 KB) or the EPUB (107 KB).
  1. What is a lead magnet? A lead magnet is something useful given away free in exchange for an email address. What makes one work, the usual formats, and how it differs from an ebook.
  2. What is a reflowable ebook? A reflowable ebook has no fixed pages: its text rearranges to fit the screen and the reader's type size. What that changes, and why Chapbook's EPUB works this way.
  3. What is a fixed-layout ebook? A fixed-layout ebook keeps every page exactly as designed instead of reflowing. What it gives up, when it is worth it, and what Chapbook does instead.

Questions people ask

What is the difference between EPUB and PDF?

An EPUB reflows its text to fit the reader's screen and chosen type size; a PDF keeps fixed pages, exactly as typeset.

Which should I use for a lead magnet?

A PDF suits most lead magnets, because it keeps the designed layout and opens on any device. Offer the EPUB as well for readers who read on an e-reader.

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