KDP Book Formatting Guide

What file types KDP accepts

The critical distinction: an eBook reflows, a print book does not. A Kindle file has no fixed pages: the reader chooses the font size and the text rearranges itself. A PDF is fixed. Everything else about formatting follows from that one fact.

Formatting a Kindle eBook

Because the text reflows, you are not designing pages. You are defining structure and letting the device lay it out.

Which means:

• Use real heading styles. Apply Heading 1 to chapter titles in Word. Do not fake a heading by making text big and bold: Kindle cannot see the difference, and your table of contents depends on it.
• Never use manual page breaks to create chapters. Use a proper page break before each Heading 1.
• Do not indent with the space bar or the tab key. Set a first-line indent in the paragraph style. Manual tabs render as random gaps on a Kindle.
• Do not fix your font size. The reader controls it. Fixing it fights the device and produces unreadable results at some settings.
• Avoid headers, footers and page numbers. They mean nothing in a reflowable file.
• Keep tables simple, or turn them into images. Complex tables collapse on small screens.

The linked table of contents

This is a genuine rejection cause and a very common one.

A Kindle table of contents must be navigable. Each entry has to be a link that jumps to its chapter. A typed list of chapter titles with page numbers beside them is worse than useless in a reflowable book, where page numbers do not exist.

The fix is mechanical. Apply Heading 1 to every chapter title, then insert an automatic table of contents. Word builds it from the headings and every entry becomes a working link. Kindle Create does the same thing without you having to think about it.

Then open the file in Kindle Previewer and click every entry. If one does not jump, the heading style is not applied.

Formatting a paperback or hardcover

Print is the opposite problem. Pages are fixed, and every dimension has to be right before you upload, because the cover is sized from the page count, and the page count is a product of the interior.

So the order matters: finish the interior, count the pages, then build the cover. Doing it the other way round means rebuilding the cover.

Trim size

Trim size is the physical dimensions of the finished book. KDP offers many; in practice a handful are used.

Trim size is a cost decision as well as a design one. "Large" trim: anything wider than 6.12" or taller than 9": carries a higher per-page printing rate. On Amazon.com, black ink goes from $0.012 to $0.017 per page. On a 300-page book that is $1.50 extra per copy, permanently. See how printing costs are calculated.

Trim also affects page count, which affects printing cost again. The same manuscript at 5" × 8" runs substantially longer than at 6" × 9", because fewer words fit on each page.

Margins and the gutter

Two different things, and the second one is where books go wrong.

Outside margins are the white space at the top, bottom and outer edge. KDP requires a minimum of 0.25", but 0.5" to 0.75" looks far better and is what professional books use.

The gutter is extra space on the inside edge, next to the spine. It has to be there because a bound book curves as it opens, and text set too close to the spine disappears into the binding. Critically, the gutter must grow with page count: a thick book curves more.

These are minimums, not targets. Add a little. Text crammed against the spine is the single most recognisable marker of an amateur interior, and it is invisible on screen. You only see it when you hold the proof.

Bleed: when you need it

Bleed means your images or colour blocks extend past the trim line, so that when the page is cut there is no white sliver at the edge.

You need bleed if anything (a photograph, a background colour, a decorative rule) runs to the edge of the page. You do not need it for a text-only book, and most novels do not.

If you use bleed, extend artwork 0.125" beyond the trim on the top, bottom and outer edges. Never on the inside edge, which is bound.

Bleed does not change your printing cost. Neither does matte versus glossy cover finish. Both are free choices, so make them purely on how you want the book to look.

Images and resolution

The most common technical rejection in print, and it is entirely avoidable.

• Print interiors need 300 DPI at the size the image actually appears on the page. A 300 DPI image blown up to twice its size becomes a 150 DPI image and will look soft in print.
• Embed the images. Do not link them from your hard drive.
• Convert to greyscale for black-ink books. Colour images printed in black ink often turn to mud. Convert deliberately and check the contrast yourself.
• For eBooks, do the opposite: compress. Kindle devices never render at print resolution, and your file size directly drives the delivery fee deducted from every 70%-option sale. Uploading 300 DPI images into a Kindle file means paying, forever, for pixels no reader will ever see.

Which tool to use

For a straight prose book, the free tools are genuinely sufficient. Pay for Atticus or Vellum if you plan a catalogue and want the hours back.

The pre-submission checklist

Run every one of these before you upload. Most rejections die here.

eBook

• Open the file in Kindle Previewer and click every table of contents entry.
• Check on the smallest device profile as well as a tablet.
• Change the font size up and down: does anything break?
• Confirm chapters start on new pages.
• Check images render and are not enormous.

Print

• Confirm trim size in the file matches the trim size selected in KDP.
• Confirm the gutter matches your final page count.
• Confirm no text or image strays into the margin.
• Check every image is 300 DPI at its printed size.
• Confirm the page count is even: print books need an even count, and KDP will pad it with a blank page if you do not.
• Build the cover after the interior is final, using the page count.
• Order a proof copy. Non-negotiable. It costs a few dollars and it is the only way to catch what the screen hides.

Frequently asked questions

Once the interior is final you can size the cover: see Amazon book cover design and trim sizes. If a submission has already been blocked, here is what Amazon usually objects to. For the whole process end to end, start with how to self-publish a book on Amazon.