How to Convert Your Manuscript Into an Ebook That Every Store Accepts

An ebook file that fails costs you twice. KDP and Apple Books reject files with a broken table of contents or an invalid EPUB, so you lose the launch date. Files that scrape through with indents made from tabs, or a cover that appears twice, cost you the sale in the free sample, which is the first thing a browsing reader opens. The conversion itself is the easy part. Most of the work is in the Word document before any tool touches it.

EPUB is the only format you need

MOBI is finished. Amazon stopped accepting MOBI uploads for reflowable ebooks on August 1, 2021, and dropped it for fixed-layout books on March 18, 2025. KDP now takes EPUB, KPF (the output of Amazon's own Kindle Create app) and DOC or DOCX, plus a few legacy formats it does not recommend. Apple Books, Kobo and Google Play all take EPUB. One EPUB, built once, covers every store. If a tutorial still talks about MOBI, the rest of its advice is probably dated too.

Reflowable means the text re-wraps to the screen and the reader controls the font size. That is what a novel, a memoir or any text-led nonfiction needs, and it is what every tool below produces by default. Fixed layout locks each page as designed, like a PDF, and exists for picture books, comics, manga and heavily designed cookbooks. KDP's guidance is that it suits books where every page needs it, not a mix. Mostly prose with a few images means reflowable.

Step 1: Fix the manuscript before you convert it

Every conversion tool reads the structure of your Word or Google Docs file, not its appearance. Formatting built by hand comes apart in conversion.

Apply the Heading 1 style to every chapter title. Tools use that style to build the table of contents and split the chapters. A title that is just bold 18-point text in the Normal style is invisible to them.

Remove manual spacing. Do not press Enter to add space between paragraphs or to push a chapter onto a new page. Set space-after in the Normal style if you want gaps, and use Insert > Page Break at the end of every chapter. Do not use tabs or the space bar for paragraph indents. KDP's formatting guide says tab spacing does not convert; set a first-line indent of 0.2 inches in the Normal style instead. Turn on Show/Hide (the ¶ button), scan for stray tabs, double spaces and empty paragraphs, and clear them with Find and Replace.

Insert images with Insert > Pictures rather than pasting, and do not enlarge them afterwards, because that lowers the resolution. KDP asks for 300 DPI at the size the image appears, in sRGB rather than CMYK, with no transparency and no TIFF files. For reflowable books the Kindle guidelines want photographs to fill at least 60 percent of the screen width, and any image containing text, such as a chart or a map, at least 80 percent. Smaller than that and readers pinch-zoom or give up.

Do not paste the cover in as page one. Every store takes the cover as a separate upload and places it in front of the book. KDP's guide says plainly not to include it in the manuscript file.

Step 2: Choose a tool

Vellum and Atticus are the paid, purpose-built options and produce the most polished interiors with the least effort. Vellum is Mac only, with no Windows version. Atticus is the equivalent for everyone else. Both let you preview the book on simulated devices before you export.

Kindle Create is Amazon's free desktop app. It is still supported, with current downloads on the KDP help pages, and it is the simplest route to a good-looking Kindle file. Its native output, KPF, only works on Amazon. It can export EPUB for reflowable books, but if you plan to sell anywhere else, build the EPUB in another tool and upload that same file to KDP.

Reedsy Studio is a free browser editor that imports a DOCX and exports a clean EPUB from a handful of templates. Calibre converts almost anything to anything and is the tool to reach for when you need to open an EPUB and fix something by hand, because its editor shows you the HTML and CSS. Draft2Digital converts a Word file to EPUB and lets you download the result at no charge even if you never distribute through them. Since April 2026, though, a new account costs $20 to open, so it is no longer the free route it used to be.

Step 3: Add the front and back matter

Keep the front of the file short. The store's free sample is cut from the start of the book, so pages of dedications and praise push the first chapter out of it. A title page, a copyright page and a linked table of contents are enough. The copyright page carries the copyright line, the edition, and the ebook ISBN if you have one. Amazon does not require an ISBN for ebooks and does not hand out free ones for them, so the choice is yours. Our guide to getting an ISBN as a self-published author covers when buying one is worth it.

Back matter is where the next sale happens. An about-the-author page, a list of your other titles with store links, and a mailing-list link are standard. Ask for a review at the end of the story, not before it.

Step 4: Validate before you upload

Run the EPUB through EPUBCheck, the W3C's validator, at version 5.4.0 as of September 2026. It is a command-line Java tool, and Apple Books rejects any file that fails it. Then open the same file in Kindle Previewer 4, Amazon's free app for Windows and Mac. It shows how the book renders on each Kindle device and jumps straight to images, lists and tables. Version 3 is no longer supported. Test every table of contents link, page through a chapter at the largest font size, and look at every image. Then load the EPUB on a phone in Apple Books or Google Play Books and read a chapter the way a reader would.

Step 5: Know the common failures

The table of contents does not link. KDP requires a logical table of contents, the one that appears in the device's Go To menu, and strongly recommends an HTML one at the front as well. Both must be real links. A table of contents typed by hand, or one Word generated from text the tool did not recognise as headings, is text, not navigation. Fix the heading styles and rebuild.

Images break or blur. Pasted images, images enlarged after insertion, and CMYK or transparent files are the usual causes. Re-insert the originals at the right size.

Fonts embedded when they should not be. The Kindle guidelines say body text must not force a font face or size, because that overrides the reader's own settings, and Amazon strips forced text colours on upload. Embedded fonts are allowed for headings, if you have the rights to distribute the font inside an ebook. The body should stay on the reader's default. If your tool offers a body font picker, leave it alone.

The cover appears twice. If the cover sits inside the manuscript as an image page and the store also places the one you uploaded, readers see it twice at the start of the sample. Remove it from the manuscript.

Spacing collapses. Gaps made from empty lines vanish or double, and indents made from spaces come out ragged. Go back to Step 1.

Next steps

Format the Word file first, then pick the tool that fits your operating system and budget. Validate with EPUBCheck and Kindle Previewer, upload the same EPUB to every store, and read the free sample on a phone before you press publish. If the sample shows any of the problems in our read sample test, fix them now, because a formatting fault in the first pages costs more sales than one in chapter twenty. For the upload itself, our KDP guide covers the royalty and pricing choices that come after the file is accepted.