KDP formatting guide — trim, margins and bleed

KDP does not reject books for looking amateurish. It rejects them for numbers: a gutter that is too narrow for the page count, artwork that runs past the trim without bleed, a cover wrap that does not match the spine. Those are all fixable before you upload.

1. Pick the trim size first

Trim size is the page size after the printer cuts the book. Everything else follows from it: the margin box, the words per page, the spine width and the cover wrap. Changing it at the end means redoing the interior, so decide it before you lay out a single page.

KDP supports a long list of trims, but eight cover almost every self-published paperback: 5×8, 5.25×8, 5.5×8.5, 6×9, 7×10, 8×10, 8.5×8.5 and 8.5×11. Novels and non-fiction usually use 6×9 or 5.5×8.5; workbooks and coloring books use 8.5×11; children’s picture books use 8.5×8.5 or a square trim.

Two trims are charged at the higher large-trim rate: anything wider than 6.12in or taller than 9 in. That includes 7×10 and 8.5×11, which is why a 300-page workbook prints for more than a 300-page novel.

2. Margins and the gutter

KDP requires at least 0.25in on the outside edges when there is no bleed, and 0.375in when there is. The inside margin — the gutter — gets wider as the book gets thicker, because a thick book curves further into the spine when it is open.

In a word processor this means using “mirror margins” rather than one left and one right margin. The gutter is always on the inside edge: the right side of a left-hand page and the left side of a right-hand page. If you set a symmetric margin, the text will crowd the spine on every other page and KDP will flag it.

The outside margin is where your thumb goes. 0.25in is the minimum, not a target — most professionally set books use 0.5in or more for comfort, which also reduces the words per page and increases the page count.

3. Bleed, if anything touches the edge

Bleed is 0.125in of extra artwork beyond the trim edge, so the printer can cut the page without leaving a white sliver. You need it whenever an image, a colour block or a background runs to the edge of the page. Text-only interiors do not need bleed at all.

With bleed, the interior page size grows: a 6×9 page becomes 6.125×9.25in. The artwork runs into the extra area; the text stays inside the safe margin. If you set up the document at the final trim size and then add bleed later, every image shifts — set the document size once, with bleed, and keep the margin box fixed inside it.

4. Type, leading and page count

Body text is usually 10–12 point with 1.15–1.5 line spacing. A 6×9 novel at 11 point with 1.15 leading holds about 300 words a page; the same manuscript at 12 point with 1.5 leading holds closer to 250, which adds roughly 20% to the page count and therefore to the printing cost.

Page count has a hard ceiling of 828 pages for black-ink paperbacks and a floor of 24 pages. The floor catches picture books and short guides: a 20-page file cannot be uploaded, so front matter, blank versos or extra content have to bring it to 24.

KDP rounds the interior page count up to an even number. A 167-page file is billed as 168, and the spine is calculated from the billed count. That is why the same manuscript can produce a spine that is one page-width different from what you expected.

5. The cover wrap

The cover is one flat file: back cover, spine and front cover, plus bleed on all four sides. Its width is 0.125 + back cover + spine + front cover + 0.125; its height is 0.125 + trim height + 0.125.

Spine width is page count multiplied by paper thickness: 0.002252in per page for white paper and 0.0025in for cream. The 300-page example is 0.6756in on white; on cream the same page count gives 0.7500in. Keep text and logos at least 0.25in away from the spine fold — a wrap that is a few hundredths of an inch off shows up as a crooked spine.

If you change paper, page count or trim, the wrap size changes. Regenerate it rather than stretching the old file; a stretched cover is the most visible formatting error on a shelf.

6. Export and upload

Export a print-ready PDF with fonts embedded and images at 300 DPI at final size. Do not downsample below 300 DPI and do not upscale a 72 DPI image — KDP’s previewer will show it as soft or rejected. Keep the interior and the cover as two separate PDFs.

The ebook is a separate export: reflowable text, no fixed page size, no page numbers, no running heads tied to pages. Uploading the paperback PDF as the ebook is the second most common formatting mistake after a bad gutter — it “works” in the previewer and reads badly on a phone.

Trim sizes at a glance

The eight trims below cover most paperbacks. The large-trim flag matters for cost: anything over 6.12in wide or 9in tall is charged at the higher rate.

Typeface choices and line length

Body text needs a typeface that survives print at 10–12 point. A high-contrast display face looks elegant on a cover and turns into grey mush in a paragraph; a workhorse text face with a large x-height reads better at small sizes and photographs well on cheap paper. Pick the text face first and let the cover follow it, not the other way round.

Line length matters as much as type size. A 6×9 page with 0.75in margins gives a text block of about 4.5in, which holds 65–75 characters at 11 point — the range most readers find comfortable. Wider trims need wider margins, not smaller type, or the eye loses its place at the end of every line.

Use one family for the body and, at most, one for headings. Chapter openings can be a little larger, but a book that mixes three typefaces on the same page reads as a document rather than a book. Embed every font before exporting: a missing font is replaced silently by the PDF writer, and the substitution is usually obvious in print.

Images and DPI

Images need 300 DPI at the size they will print, not at some larger size that gets scaled down. A 1000×1000 pixel image placed in a 6in-wide box is 167 DPI and will look soft; the same file in a 3in box is 333 DPI and is fine. Judge DPI at final placement size, not at the file’s pixel dimensions.

Use greyscale for black-ink interiors and CMYK-aware exports where colour is involved. A colour image dropped into a black-and-white interior prints as muddy grey, and KDP charges for colour only when the interior is set up as colour — the mismatch is a common reason a proof comes back looking wrong.

Why files get rejected

The most common rejection is a margin problem: text or an image too close to the trim, or a gutter that does not match the page count. The second is bleed — artwork that reaches the trim edge without the extra 0.125in, so the cut leaves a white sliver. Both are visible in the KDP previewer before you approve the book.

The third is the cover wrap. A wrap built for a different page count stretches the spine, and a spine that is 0.05in off looks crooked on a shelf. Regenerate the wrap whenever the page count, paper or trim changes, and keep the title and any logo clear of the spine fold.

The fourth is embedded fonts and image resolution. These are less visible in the previewer and more visible in print, which is why a physical proof is worth the cost for a first book. If a proof comes back with soft images, the fix is at the source file, not in the KDP settings.

Proofing is part of formatting, not a separate step. Order a physical copy of the first book even if the previewer looks perfect: the previewer cannot show you how heavy the paper feels, how the spine cracks, or whether the cover colours match the screen. For a second book in the same format, the first proof is enough to trust the setup.

Keep a master file for each format. The paperback master, the ebook master and the cover master are three documents, not one document exported three ways. When a typo is found after publishing, you fix it in the paperback master, re-export, and upload a revision — the ebook and the cover do not need to be touched.

Blank pages are part of the file, not a gap in it. Front matter, part-title pages and blank versos all count toward the page count and the printing cost, which is why a novel with a long front matter prints for more than the same manuscript without it. Plan the front matter before you set the page count, not after the proof arrives.

Finally, check the file on a second device before uploading. A PDF that looks right in one reader can show missing fonts or a shifted margin box in another, and the KDP previewer is a third renderer with its own quirks. If all three agree, the file is ready; if they disagree, the source document is the thing to fix.

Pre-upload checklist

Run through this list before you upload. Every item is a real rejection or a real print defect, and each one is cheaper to fix in the source file than after the proof arrives.

If you want the exact numbers for your book rather than the examples here, the spine and cover calculator returns the spine, the full cover wrap and the interior size with bleed. The printing cost calculator shows what the resulting page count costs, and the royalties guide turns that into a per-copy royalty.

For a genre-specific example, the coloring book guide walks through the single-sided 8.5×11 case, where bleed and paper choice matter more than typography. If you are still at the manuscript stage, the word count guide shows how length turns into pages.

Where these numbers come from

Gutter widths, bleed, trim limits and spine constants come from Amazon KDP’s published file setup guidance, checked on the date printed at the top of this page. The spine and cover examples are computed by this site’s calculator, not typed by hand.

Sources: trim, bleed and margins, paperback submission guidelines and print options.