To format an ebook properly, build it as a reflowable file with consistent paragraph and heading styles, no manual spacing, and a working table of contents, then export it as EPUB and test it in Kindle Previewer and at least one other reading app before you upload. Reflowable means the text rewraps to fit any screen and font size the reader chooses, so your job is to control structure, not exact page appearance. For most novels and text-led non-fiction, that is the whole job.

This guide includes a few product links near the end. As an Amazon Associate, Freyja Publishing earns from qualifying purchases, at no extra cost to you.

This guide covers the technical side of ebook formatting: which file formats the stores accept, how to set up a manuscript so it converts cleanly, what to do with images, tables and special characters, and how to test before publishing. If you are trying to decide which formatting software to buy (or whether to buy any), that choice is compared in detail in Atticus vs Vellum vs Kindle Create, so it is only summarised here.

At a glance

• EPUB is the format to aim for. Apple Books, Kobo, Google Play Books and aggregators all work from EPUB, and Amazon KDP accepts EPUB too, so one well-built file can serve every store.
• Use styles, not manual formatting. Headings, body text and scene breaks should each be a named style. Tabs, repeated spaces and repeated blank lines are the most common cause of broken ebooks.
• Do not fight the reader. Readers change fonts, sizes, margins and line spacing. Fixed font sizes and hard page breaks do not survive.
• Images cost money on Amazon. At the 70% royalty rate, KDP deducts a delivery cost based on file size, so compress images sensibly.
• Test before you publish. Kindle Previewer, the free EPUBCheck validator and a real phone or e-reader will catch nearly every problem readers would otherwise report.

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Reflowable or fixed layout: decide this first

Every ebook is one of two types, and the choice shapes everything else.

Reflowable ebooks behave like a web page. Text rewraps to fit the screen, and readers can change the font, the size and often the margins and line spacing. Novels, memoirs, most non-fiction, and anything that is mainly text should be reflowable. This is what readers expect, and it is what the stores handle best.

Fixed-layout ebooks keep each page exactly as designed, like a PDF. Text cannot be resized in the usual way. Fixed layout suits picture books, comics, cookbooks with designed spreads, and highly visual workbooks. It is harder to produce, larger in file size and less comfortable to read on a phone. If you are publishing an illustrated children’s book, the specific considerations are covered in how to self-publish a children’s book.

If you are unsure, choose reflowable. A text-led book forced into fixed layout reads badly on small screens and gives readers no control.

Ebook file formats compared

The format you upload is not always the format readers receive. Amazon, for example, converts uploaded files into its own delivery format. What matters is which file you build and keep as your master.

Format	What it is	Where you can use it	Best for
EPUB (reflowable)	The open industry standard, maintained under the W3C. A packaged set of HTML, CSS and image files.	Apple Books, Kobo, Google Play Books, Barnes & Noble, aggregators such as Draft2Digital, and Amazon KDP.	Almost every text-led book. Your best master file.
KPF	Kindle Package Format, produced by Amazon’s free Kindle Create tool.	Amazon KDP only.	Authors selling only on Amazon who want a free tool.
DOCX (Word)	A word-processing file that KDP and some aggregators convert for you.	KDP, Draft2Digital and others, with automatic conversion.	Simple novels with clean styles. Least control over the result.
Fixed-layout EPUB	EPUB with every page positioned exactly.	Apple Books, Kobo and others; Amazon handles fixed layout through Kindle Create and its own tools.	Picture books, comics, designed cookbooks.
PDF	A fixed page designed for print.	Accepted by KDP for some languages, but converts poorly for reading on small screens.	Print interiors, not ebooks.
MOBI	Amazon’s older Kindle format.	Legacy only. KDP stopped accepting MOBI for fixed-layout ebooks in March 2025 and recommends other formats.	Nothing new. Do not build around it.

According to KDP’s help pages on supported formats, Amazon currently accepts Word, KPF, EPUB, HTML, RTF, plain text and, for certain languages, PDF. If you plan to sell beyond Amazon, building a clean EPUB gives you one file you can upload everywhere. If you plan to stay exclusive, it is worth reading the guide to Kindle Unlimited and KDP Select first, because exclusivity affects which stores you will need files for.

Ways to produce your ebook file

There are five realistic routes. All can produce a professional reflowable ebook; they differ in cost, control and how much you need to learn.

Route	Cost	Skill needed	Output	Watch out for
Upload a styled Word file	Free	Low	Store converts it	Little control; messy styles show up as errors
Kindle Create	Free	Low	KPF (Amazon only)	Cannot be used on other stores
Free web formatters (Draft2Digital’s formatting tool, Reedsy Book Editor)	Free	Low	EPUB, and print PDF in some cases	Limited design choices
Dedicated formatting software (Vellum, Atticus)	One-time purchase	Low to medium	EPUB and print PDF	Vellum is Mac-only; compare features before buying
Hand-built or open-source tools (Calibre, Sigil, Pandoc)	Free	High	EPUB with full control	Steep learning curve; easy to introduce errors

Hiring a formatter is a sixth option. Quotes vary widely with the length and complexity of the book, so ask for a sample chapter, confirm you will receive the EPUB and any source files, and check what corrections cost after delivery. For a full comparison of the paid tools, including current prices and who each suits, see Atticus vs Vellum vs Kindle Create. For formatting software in the context of everything else an author needs, see the author toolkit guide.

How to prepare your manuscript: step by step

Whichever route you choose, these steps prevent most conversion problems. Do them on a final, edited manuscript. Formatting before editing is finished means formatting twice; the self-editing guide covers what needs to be done first.

1. Save a clean copy. Work on a duplicate of your final manuscript so you can always return to the original.
2. Turn on formatting marks. In Word, show paragraph marks and hidden characters so you can see tabs, double spaces and stray breaks.
3. Remove manual spacing. Use find and replace to strip tabs at the start of paragraphs, double spaces between words and runs of empty paragraphs.
4. Apply heading styles. Make every chapter title Heading 1 and any sub-sections Heading 2 or 3. Tables of contents and navigation are built from these.
5. Set your body text style. Choose either a first-line indent with no space between paragraphs (the usual choice for fiction) or no indent with a space between paragraphs (common in non-fiction). Never both.
6. Style the first paragraph of each chapter. Convention is no indent on the first paragraph after a heading or scene break. Create a separate style for it.
7. Mark scene breaks consistently. Use a centred symbol (such as three asterisks) in its own style rather than a blank line, which can disappear at the top or bottom of a screen.
8. Insert chapter breaks properly. Use a page break before each chapter (or a style set to start on a new page), not repeated returns.
9. Use real characters. Check that quotes are curly, that dashes are true em or en dashes, and that ellipses are consistent.
10. Keep front matter short. Retail previews and samples start at the beginning of the file, so place long acknowledgements, author notes and also-by lists at the back.
11. Add back matter that helps readers continue. A short author note, the next book in the series and a sign-up invitation belong after the final chapter.
12. Export and test. Produce your EPUB (or KPF), then run through the testing checklist below.

Typography and layout choices that survive on every device

Fonts

Readers choose their own fonts on almost every device, and many reading apps override fonts set by the publisher unless the reader opts in. Design for that. Leave body text in a standard serif, use bold and italics where meaning requires them, and avoid decorative fonts for body text. If you want a distinctive look for chapter titles, a small image of the title is safer than an embedded display font, but keep it light and always include the text version for navigation and accessibility.

Font size and line spacing

Do not set fixed point sizes for body text or fixed line spacing. Leave both at the default so readers can adjust them. Headings can be relatively larger than body text, which scales correctly.

Special characters

Em dashes, curly quotes, accented letters and symbols such as the copyright sign convert reliably when they are typed or inserted as real characters. Problems usually come from text pasted in from web pages or older files. Searching the finished EPUB for stray straight quotes is a quick final check.

Links and the table of contents

An ebook needs two kinds of table of contents: the navigation menu that the reading app shows, built from your headings, and usually a linked contents page inside the book. Amazon’s Kindle Publishing Guidelines expect working navigation, and most formatting tools generate both from Heading 1 styles. Test every link. Because external links are not tappable on every device, write any web address the reader needs as readable text as well.

Images, tables and other complex content

Images

Use JPEG for photographs and PNG for line art or images with sharp edges. Size images for screens rather than print. A picture prepared for a print interior at a very high resolution can bloat the file without looking any better on a phone. Compress each image and check it on a small screen.

File size matters on Amazon. When you choose the 70% royalty option, KDP deducts a delivery cost based on the size of the converted file; in the US marketplace this is US$0.15 per megabyte at the time of writing (October 2026), with different rates in other marketplaces. A text-only novel is usually tiny, but a book with dozens of large photographs can lose a meaningful amount per sale. Rates change, so check KDP’s pricing help pages.

Add alternative text (a short description) to every meaningful image so screen readers can describe it. Most formatting tools have a field for this.

Your cover file

The ebook cover is uploaded separately from the interior on KDP. According to KDP’s cover image guidance, the ideal size is 2,560 pixels high by 1,600 pixels wide, as a JPEG or TIFF in RGB colour, under 50 MB. Other stores publish their own specifications, but a cover at that size and ratio works widely. If you are commissioning one, the guide to choosing a cover designer explains what to ask for.

Tables

Wide tables are the hardest element to get right in a reflowable ebook because phone screens are narrow. Keep tables to two or three columns where possible. If a table must be wide, consider splitting it, turning it into a list, or using an image of the table with the full data available as text nearby. Test tables in portrait orientation on a phone.

Footnotes, boxes and media

Footnotes become linked endnotes or pop-up notes in most ebooks. Check that each note links back to its place in the text. Sidebars and shaded boxes render differently from one app to another, so keep their formatting simple and make sure the content still makes sense if the border or shading disappears.

EPUB 3 can include audio and video, and some apps (Apple Books, for example) can play them, but Kindle does not support embedded media in standard ebooks. If your book depends on media, offer it through a web page the reader can visit and describe it in the text.

Accessibility is part of good formatting

A well-structured ebook is already most of the way to being accessible: real headings, a working table of contents, alternative text on images and a logical reading order. This matters to readers who use screen readers or large text, and it increasingly matters legally. The European Accessibility Act has applied to ebooks sold to consumers in the European Union since 28 June 2025, with some exemptions for very small businesses. Requirements and exemptions differ by country and circumstance, so if you sell into the EU, check how the rules apply to you and add accessibility information where your distributor asks for it.

Testing checklist before you upload

Allow an hour or two for testing. It is the cheapest quality control in publishing.

• Run the EPUB through EPUBCheck, the free validator maintained under the W3C, or the validation built into your distributor’s upload process. Apple Books in particular rejects files with errors.
• Open the file in Kindle Previewer (free from Amazon) and look at it in phone, tablet and e-reader views.
• Open it in at least one other reading app, such as Apple Books or Kobo, or in Calibre’s viewer on a computer.
• Read the first chapter on an actual phone, in portrait orientation.
• Change the font size to the largest and smallest settings and check that nothing breaks.
• Tap every entry in the table of contents and every internal link.
• Check the first line after every heading and scene break for unwanted indents.
• Look for stray straight quotes, double spaces and empty pages.
• Check images for blurring, cropping and alternative text.
• Confirm the front matter is short enough that the sample reaches the story or the substance quickly.

Platform notes

Amazon KDP converts every upload into its own delivery format, so check the converted book in KDP’s online previewer before publishing, even if your EPUB looked perfect elsewhere. If you also publish a paperback, the print interior is a separate file with its own requirements; print on demand vs traditional printing covers the print side.

Apple Books, Kobo and Google Play Books all work from EPUB, and Apple applies strict validation. Aggregators such as Draft2Digital and PublishDrive deliver one upload to many stores; Draft2Digital vs PublishDrive compares them. Keep one master EPUB and upload the same file everywhere so corrections stay consistent.

Common mistakes

• Indenting with tabs or spaces. These either vanish or create uneven indents. Use the paragraph style’s first-line indent.
• Using blank lines to create space. Empty paragraphs collapse or create blank screens. Set spacing in styles.
• Formatting before the edit is final. Every late change means re-exporting and retesting every edition.
• Locking font sizes or line spacing. Readers who need larger text are let down, and some devices ignore the setting anyway.
• Uploading a print PDF as the ebook. It will not reflow and is hard to read on small screens.
• Using Kindle Create’s KPF as your only file. If you later go wide, you will need to rebuild the ebook from scratch.
• Uncompressed images. Large files cost delivery fees on Amazon and download slowly.
• A long run of front matter. Readers browsing a sample may never reach chapter one.

If you are unsure where each opening section belongs, this guide to how a prologue differs from a preface or foreword sets out the usual order.

Sources this guide draws on: Amazon KDP Help pages on supported ebook formats, eBook cover image guidelines and royalty delivery costs; Amazon’s Kindle Publishing Guidelines; the W3C EPUB 3.3 Recommendation and EPUBCheck documentation; and the European Commission’s information on the European Accessibility Act, checked in October 2026.

Frequently asked questions

What is the best file format for an ebook?

EPUB, for almost every text-led book. It is the open industry standard, every major store accepts it, and Amazon KDP accepts it too. Building one clean EPUB means you can publish anywhere without reformatting.

Can I upload a Word document to KDP?

Yes. KDP accepts DOC and DOCX files and converts them automatically. It works well for simple novels with clean, consistent styles, but you have less control over the result than with an EPUB, so check the converted file carefully in the online previewer.

Do I need special software to format an ebook?

No. Free options such as Kindle Create, Draft2Digital’s formatting tool, the Reedsy Book Editor and Calibre can all produce acceptable files. Paid tools such as Vellum and Atticus save time and offer more design choices, which matters most if you publish often.

Should I use a fixed layout for my book?

Only if the design of each page is essential, as in picture books, comics and some cookbooks. For novels and most non-fiction, fixed layout makes reading harder on phones and removes the reader’s control over text size.

How do I check my EPUB for errors?

Run it through EPUBCheck, the free validator maintained under the W3C, then preview it in Kindle Previewer and at least one other reading app. Many distributors also validate files during upload and report errors.

Good ebook formatting is mostly invisible. If readers never notice the layout and simply keep reading, the job is done. Build clean styles, keep one master EPUB, test on real screens and your book will look professional wherever it is sold.