For most professionally produced, text-led books, EPUB is the best format to upload to Amazon KDP. It is an open, reflowable ebook format, and KDP recommends checking it with Kindle Previewer before uploading. KPF is also a strong option when the book is built in Amazon’s free Kindle Create tool. A clean DOCX can work for a simple manuscript, but complex styling may convert unpredictably.
Do not build a new Kindle workflow around legacy MOBI files. KDP’s current help page says it stopped accepting MOBI for fixed-layout ebooks in March 2025. Always verify the live KDP format page before publishing because accepted inputs and platform limits can change.
|
Format |
Best use | Advantages | Watch-outs |
| EPUB | Most professional reflowable ebooks | Open standard; strong structure; portable production master | Validate and check in Kindle Previewer |
| KPF | Kindle-only workflow using Kindle Create | Designed for Kindle devices; built-in themes and TOC tools | Less portable outside Amazon workflow |
| DOC/DOCX | Simple, clean manuscripts | Easy for authors; accepted by KDP | Complex Word formatting may convert badly |
| HTML package | Controlled technical workflows | Direct control of markup and styles | Requires clean HTML/CSS and careful packaging |
| Limited-language or fixed-page cases | Preserves pages | Poor choice for ordinary reflowable reading | |
| MOBI | Legacy files only | May exist in older libraries | Not accepted by KDP for fixed-layout uploads since March 2025 |
The best production master and the best KDP upload file are not always identical. Keep an editable source manuscript, archive a validated EPUB when possible, and upload the file type that gives the cleanest result in Kindle Previewer.
In a reflowable ebook, the reader can change font size, typeface, line spacing, margins, and device orientation. The text repaginates automatically. Novels, memoirs, business books, and most text-led nonfiction should use this approach.
Reflowable design is structural rather than page-based. A heading is marked as a heading; a paragraph is a paragraph; a quotation is a quotation. Avoid instructions such as “see the chart on the next page” because page boundaries change by device and reader settings.
Fixed layout or Print Replica may suit picture books, comics, textbooks, or visual manuals in which every element must remain in a precise position. The tradeoff is less flexible text, more demanding testing, and possible limitations on smaller screens or accessibility.
Do not choose fixed layout merely to preserve Word pagination. If the book is mainly running text, reflowable EPUB almost always provides a better Kindle experience.
Duplicate the final edited manuscript before formatting. Use the copy for cleanup and conversion, and keep the source in version control or dated backups. Confirm that the text is final enough that major edits will not repeatedly break navigation and styling.
Delete running headers, footers, page numbers, crop marks, blank pages, and manually typed line breaks. Replace tabs and repeated spaces used for alignment. Ebooks do not need mirrored margins, gutters, or a print trim size.
Apply one body style and real heading levels. Use Heading 1 for major sections or chapters, Heading 2 for subsections, and Heading 3 only when needed. Create paragraph styles for quotations, lists, captions, and scene breaks instead of formatting each paragraph by hand.
Use paragraph settings for first-line indents and spacing. Never press Tab or insert multiple spaces to create an indent. Avoid adding extra blank paragraphs between every paragraph; that can produce inconsistent gaps on different devices.
Typical front matter includes a title page, copyright page, optional dedication or epigraph, and a linked table of contents. Keep it concise so readers who open a sample reach the book’s substance quickly. Mark the intended beginning of the book when the chosen tool supports it.
Generate the table of contents from heading styles. KDP expects a logical reading order and useful navigation. Every TOC entry should open the correct section, and chapter navigation should not include empty anchors or duplicate headings.
Insert images in the reading order and size them for the display rather than the original camera resolution. Use clear, rights-cleared images and avoid text embedded in pictures when live text is possible. Add meaningful alt text for informative images; mark decorative images appropriately in the production workflow.
Test diagrams at phone width. If labels become unreadable, simplify the graphic, split it into panels, or provide an accessible text explanation. Check that images do not force horizontal scrolling.
Wide tables often fail on small screens. Convert them to shorter tables, stacked comparisons, or repeated label-value blocks. Use real lists instead of typed bullets. Link footnote references in both directions when the conversion tool supports it, and ensure superscripts remain legible.
For a broad retail-ready workflow, export or convert to a standards-compliant reflowable EPUB. For a Kindle-only DIY workflow, import the manuscript into Kindle Create and export KPF. A simple DOCX upload can be acceptable when the document uses clean styles and has few complex elements.
Run the EPUB through an EPUB validator when EPUB is the deliverable. Then open the exact KDP upload file in Kindle Previewer. Automated validation catches structural errors; visual preview catches design problems. You need both.
Check at least a phone-sized view, a tablet view, and an E Ink view where available. Change font size and orientation. Inspect the first page of every chapter, long headings, lists, images, tables, links, footnotes, and the final back-matter call to action.
Enter the book details carefully, upload the manuscript and cover, and use KDP’s preview and quality messages. Resolve warnings rather than assuming they are harmless. Re-download or re-open the processed preview if the workflow permits and compare it with the approved file.
After release, check the live sample and detail page. Review KDP’s Quality Notifications Dashboard and reader feedback. Correct meaningful errors in the source, regenerate the file, preview again, and then replace the manuscript.
Before: each paragraph begins with a typed Tab, and blank lines are added for spacing. Result: indents vary and large gaps appear after conversion.
After: the body paragraph style uses a consistent first-line indent, with spacing controlled by the style. Result: the layout adapts predictably when readers change font size.
Before: chapter titles are plain body text made larger and bold. Result: the converter may not recognize chapters, so the navigation is incomplete.
After: every chapter title uses Heading 1 and the TOC is generated from that structure. Result: chapter links and reading order are reliable.
Before: a six-column table copied from a print layout shrinks until the text is unreadable on a phone.
After: the data is reorganized into short three-column tables or stacked factor-and-answer blocks. Result: readers can understand the comparison without zooming or horizontal scrolling.
These are platform rules, not timeless specifications. Verify the KDP help page on the day you upload.
Remove manual page breaks and empty paragraphs around section boundaries. Check whether a heading style or fixed-height image forces content to a new screen.
Reapply structural heading styles, rebuild the TOC, and confirm that each link points to a unique anchor. Avoid duplicate chapter names without distinct internal targets.
Use a restrained stylesheet and avoid relying on unsupported local fonts. Let readers control body typography. Reserve font embedding or special styling for a justified design need and test it across devices.
Replace low-resolution sources, remove unnecessary whitespace from the image canvas, and set responsive dimensions. Compress sensibly without making labels illegible.
Clean the source styles or switch to a controlled EPUB/KPF workflow. A file that looks correct in Word can contain hidden formatting that converts unpredictably.
EPUB is the best general upload format for most professionally produced reflowable ebooks. KPF is a strong option for books built with Kindle Create.
Readers may encounter legacy MOBI files, but authors should follow KDP’s current upload guidance. KDP states that MOBI is no longer accepted for fixed-layout ebooks as of March 2025.
Yes. KDP accepts DOC/DOCX, and simple files often convert well. Complex formatting should be checked closely in Kindle Previewer.
KDP lists PDF as an additional accepted format for certain languages, but PDF is page-based and often unsuitable for ordinary reflowable reading. Use EPUB or KPF unless fixed pages are truly required.
KDP does not require an ISBN for a Kindle ebook and assigns an ASIN. If the ebook uses an ISBN for wider distribution, it must be different from the print editions.
The source is structurally clean, the output validates, navigation works, representative devices render correctly, KDP reports no unresolved quality issues, and the metadata matches the approved book.
Use EPUB for the strongest general-purpose Kindle workflow, or KPF when Kindle Create is the production tool. Clean the manuscript before conversion, rely on structural styles, test every special element, and preview the exact upload file. Professional Kindle formatting is not about making one screen look like a printed page; it is about making the book adapt reliably to every supported reading environment.
If you want a production-ready file without rebuilding the manuscript yourself, review ISBN Services’ ebook conversion service, ebook formatting service, ebook distribution service, and manuscript-preparation guide.
