Choose a KDP ebook file format from the book’s behavior, not its filename. A text-led book that should reflow can use an EPUB candidate containing navigation, cover, and colophon, subject to current KDP requirements.
When working on KDP ebook file format, consider a six-chapter business book intended to support font resizing on phones. The task is complete only when need for font resizing and inclusion of colophon or back matter can both be confirmed after the saved output is reopened. An export message by itself does not answer the search question.
Decide what success means for this book
For this example—a six-chapter business book intended to support font resizing on phones—the first decision is whether need for font resizing has a known starting value. The final decision is whether inclusion of colophon or back matter survives export and reopening. Keeping those two moments separate prevents a temporary editor display from becoming the handoff criterion.
Preserve the received manuscript, edit a production duplicate, and write the EPUB separately. With KDP ebook file format as the goal, those three files keep the source, intentional edits, and packaged book distinct.
The direction is one-way: preserved source, editable duplicate, separately written EPUB, then a reopened EPUB. The method does not recreate the manuscript from the EPUB or treat the package as an editing source.
Build a representative test case
Build the example around a six-chapter business book intended to support font resizing on phones. Keep the part that could genuinely fail. If the risk concerns need for fixed image placement, include the exact chapter, character, path, or label that creates that risk. Removing it for a cleaner demo would produce an easy pass with no value for the real book.
Check four independent facts
- Need for font resizing: while you classify pages as text-led or fixed-placement, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from need for fixed image placement.
- Need for fixed image placement: while you check current supported formats in official KDP help, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from complete logical navigation and cover.
- Complete logical navigation and cover: while you prepare chapters, navigation, cover, and back matter, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from inclusion of colophon or back matter.
- Inclusion of colophon or back matter: while you export and check package integrity, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from need for font resizing.
Complete the operation in order
- Classify pages as text-led or fixed-placement. Before moving on, confirm need for font resizing; if it differs from the expected state, correct that step rather than compensating later.
- Check current supported formats in official KDP help. Before moving on, confirm need for fixed image placement; if it differs from the expected state, correct that step rather than compensating later.
- Prepare chapters, navigation, cover, and back matter. Before moving on, confirm complete logical navigation and cover; if it differs from the expected state, correct that step rather than compensating later.
- Export and check package integrity. Before moving on, confirm inclusion of colophon or back matter; if it differs from the expected state, correct that step rather than compensating later.
- Resize text in the intended preview environment. Before moving on, confirm need for font resizing; if it differs from the expected state, correct that step rather than compensating later.
Walk the example from source to handoff
During step 1, classify pages as text-led or fixed-placement. In the case of a six-chapter business book intended to support font resizing on phones, check need for font resizing before changing anything else. This prevents choosing from the extension alone. If the observation is unknown, repeat that step with the production duplicate instead of editing the master manuscript.
During step 2, check current supported formats in official KDP help. In the case of a six-chapter business book intended to support font resizing on phones, check need for fixed image placement before changing anything else. This prevents forcing a fixed-design work into reflow. If the observation is unknown, repeat that step with the production duplicate instead of editing the master manuscript.
During step 3, prepare chapters, navigation, cover, and back matter. In the case of a six-chapter business book intended to support font resizing on phones, check complete logical navigation and cover before changing anything else. This prevents presenting local valid status as guaranteed KDP acceptance. If the observation is unknown, repeat that step with the production duplicate instead of editing the master manuscript.
During step 4, export and check package integrity. In the case of a six-chapter business book intended to support font resizing on phones, check inclusion of colophon or back matter before changing anything else. This prevents choosing from the extension alone. If the observation is unknown, repeat that step with the production duplicate instead of editing the master manuscript.
During step 5, resize text in the intended preview environment. In the case of a six-chapter business book intended to support font resizing on phones, check need for font resizing before changing anything else. This prevents forcing a fixed-design work into reflow. If the observation is unknown, repeat that step with the production duplicate instead of editing the master manuscript.
What the example showed
The trial produced this observation: The test book exported 5 chapters with writingMode=horizontal and version 1.7. Inspection returned spine=9, images=1, missing=0, nav=true, NCX=true, and valid=true.
That value belongs to the files and settings used for this example. It supports the documented sequence; it does not turn KDP ebook file format into a promise for every manuscript, reading system, or retailer.
The untested boundary is equally important: valid=true is a local package output, not retailer acceptance or identical rendering in every reader. Outside this scope: Copyright clearance, identical rendering in every reader, and retailer acceptance are outside scope. Add retailer preview, device testing, accessibility review, or rights clearance when the book requires those decisions.
The W3C EPUB 3.3 specification defines the EPUB navigation document as a required publication component.
KDP requirements can change, so verify the current list in Amazon KDP’s supported ebook formats help immediately before submission.
Recover from the three likely mistakes
- Choosing from the extension alone: go back to “classify pages as text-led or fixed-placement,” then re-examine need for font resizing. Change only the responsible input so the next comparison remains meaningful.
- Forcing a fixed-design work into reflow: go back to “check current supported formats in official KDP help,” then re-examine need for fixed image placement. Change only the responsible input so the next comparison remains meaningful.
- Presenting local valid status as guaranteed KDP acceptance: go back to “prepare chapters, navigation, cover, and back matter,” then re-examine complete logical navigation and cover. Change only the responsible input so the next comparison remains meaningful.
Decide whether Rune Studio fits
Rune Studio is a candidate when an editor wants manuscript work and EPUB preparation in one Mac application for a project involving a six-chapter business book intended to support font resizing on phones. Product documentation describes available functions; the observation above documents only this example.
See the product on the Rune Studio website. Keep the adoption boundary explicit: copyright clearance, identical rendering in every reader, and retailer acceptance are outside scope.
Take the next step
Start with this action: classify pages as text-led or fixed-placement. Then follow the remaining steps until inclusion of colophon or back matter can be reproduced from the reopened publication. That is the practical finish line when working on KDP ebook file format.