KDP book formatting

What KDP needs from you

Two separate products, uploaded separately, even though they are the same book:

• Kindle ebook — one EPUB file, plus a cover image. Amazon converts the EPUB to its own format when you upload.
• Paperback or hardcover — a print-ready PDF of the interior at your exact trim size, plus a separate cover PDF sized to the back cover, spine and front cover together.

KDP will still accept a .docx for the ebook. It works, and it is how a lot of first books get published. What you lose is any control over the result and any chance to see it before Amazon's converter has had its way with it.

Step 1 — Choose the trim size

Do this first. Trim size determines the page count, and the page count determines the gutter margin, the spine width and the print cost — so changing it later invalidates all three.

• 6" × 9" — the most common on KDP for both fiction and non-fiction. The safe default.
• 5.5" × 8.5" — the other standard for novels. Feels more like a trade paperback from a publisher.
• 5" × 8" — smaller and more literary; makes a thicker book from the same manuscript.
• 4.25" × 7" — mass-market size. Thickest of all for a given word count.
• 8.5" × 11" — workbooks, manuals, anything with worksheets.

Pick the size your genre's shelf actually uses. Take three comparable books off your own shelf and measure them; that is more reliable than any list, including this one.

Step 2 — Set the margins

Outside, top and bottom must be at least 0.25 in — or 0.375 in if your interior uses bleed.

The inside margin, the gutter, is the one that catches people. A thicker book curves more at the spine, so more of the inner margin disappears into the binding. KDP therefore requires a gutter that grows with page count:

These are minimums, not recommendations. Books set at the minimum read as cramped. For a novel at 6" × 9", something like 0.875 in inside and 0.75 in outside looks like a book rather than a document that met a requirement.

Step 3 — Decide about bleed

Bleed is only needed when something on an interior page is meant to reach the edge of the paper: a full-page photograph, a coloured band, a map. A text-only novel does not need it and should not use it.

If you do need it, extend the artwork 0.125 in beyond the trim on the outer edges, and raise the outside margin to 0.375 in. Printers cut through a stack of books at once and the blade wanders slightly; bleed is what stops a white sliver appearing at the edge of the image.

Step 4 — Format the interior

What KDP requires, and what readers expect, are not quite the same list.

Required:

• Embedded fonts. A font that is not embedded is substituted, and the pagination changes.
• Images at 300 DPI at final printed size — not 300 DPI at whatever size they happen to be.
• An even page count, at least 24 pages. Odd counts get a blank page added.
• Every page at exactly the trim size. A single stray page at a different size fails the upload.

Expected by readers, and noticed when missing:

• Chapters starting on a right-hand (recto) page.
• Running heads and page numbers suppressed on chapter-opening pages.
• No page number on blank pages or in the front matter proper.
• First paragraph of a chapter not indented; subsequent ones indented.
• No widows or orphans — a single line stranded at the top or bottom of a page.
• Consistent scene-break treatment throughout.

Step 5 — Work out the spine, then make the cover

Only now, with the interior final and the real page count known. KDP's spine formula is the page count multiplied by the paper's per-page thickness:

So a 320-page novel on cream paper has a spine of 320 × 0.0025 = 0.8 in. The full cover is then back cover + spine + front cover, with 0.125 in of bleed around the whole sheet.

Use the spine width calculator if you would rather not do it by hand — it covers both KDP and IngramSpark, which is worth checking if you plan to use both.

Step 6 — Check before you upload

KDP's previewer catches size and margin violations, and it is worth using. It does not catch the things that make a book look self-published: a heading orphaned at the foot of a page, a chapter that opens on a verso, an image that is technically 300 DPI but was upscaled to get there, a table of contents pointing at a chapter you renamed.

Read the whole interior PDF at 100% before you upload it. Not on a phone, and not skimmed — you are looking for the pages that are wrong rather than the ones that are ugly.

The Kindle ebook is a different job

Everything above is about print. The ebook shares your text and almost nothing else, because there are no pages: the reader picks the type size and the text rewraps around it.

What changes:

• No page numbers, no running heads, no fixed margins. Kindle supplies all of that.
• Relative type sizes, never absolute — a 12pt paragraph ignores the reader's own setting.
• A navigable table of contents, generated from the headings, not typed.
• Images sized for screens, with alt text.
• Scene breaks as a styled element, not blank lines — blank lines collapse.

Upload EPUB rather than .docx. You keep control of the styling, and you can check the file in Kindle Previewer before Amazon converts it.