The correct print-on-demand book margins depend on two things: which platform you publish to and how many pages your book has. On Amazon KDP, the inside (gutter) margin starts at 0.375″ for shorter books and scales up to 0.875″ for books approaching 828 pages. On IngramSpark, a flat minimum of 0.5″ on all sides applies. Set these in Microsoft Word before you submit, or your book will be rejected or print with text disappearing into the spine.
What Are the Four Margin Zones, and Why Is the Gutter Always Largest?
Every page in a print book has four margin zones: inside (gutter), outside, top, and bottom. The gutter is the margin along the spine edge, the side where pages are bound together. Because the binding physically consumes space, text near the gutter gets harder to read as the book thickens, which is why the inside margin is always set larger than the other three.
The outside margin is the edge opposite the spine, the side you grip when holding the book. Top and bottom margins frame the text block vertically and usually also carry headers, footers, and page numbers. All four zones must clear the platform’s minimums, but only the gutter minimum changes with page count. Remember that the top and bottom margins are not purely whitespace: they hold your running headers, footers, and page numbers, so the text block itself sits inside those figures rather than butting up against them. In the books we format, the single most common cause of a spine-side reading problem is a gutter that was set correctly for a 200-page draft and never revisited after the manuscript grew past 400 pages, once the extra paper thickness pulled the inner text further into the curve of the spine.
What Are KDP’s Margin Requirements by Page Count?
Amazon KDP uses a sliding scale for the inside margin that grows as your page count rises. According to KDP’s Set Trim Size, Bleed, and Margins guidance, the current minimum gutter values are:
- 24–150 pages: 0.375″ gutter
- 151–300 pages: 0.5″ gutter
- 301–500 pages: 0.625″ gutter
- 501–700 pages: 0.75″ gutter
- 701–828 pages: 0.875″ gutter
The outside, top, and bottom margins on KDP must be at least 0.25″ for standard (non-bleed) books. If your book contains any element that bleeds to the edge of the page, such as a full-page illustration or a background colour that runs to the trim, those three margins increase to a minimum of 0.375″.
One consequence of this tiered structure catches authors out repeatedly: if you sit near a page-count boundary, adding or cutting content can push you across a threshold and demand a larger gutter. A 299-page manuscript and a 301-page manuscript carry different minimum gutters. Confirm your final page count before you lock the margins, not before the last round of edits.
The same gutter table applies to KDP hardcovers as well as paperbacks, so a title released in both formats can share one interior margin setup. If you work in millimetres rather than inches, the tiers convert to roughly 9.6 mm, 12.7 mm, 15.9 mm, 19.1 mm, and 22.2 mm; Word will accept either unit, but keep one convention throughout the document so a stray rounded value never slips a margin under the minimum.
Need help with the technical aspects of self-publishing? Get a free quote.
Thank you. Your enquiry is on our desk.
We've received your message and will get back to you by email, usually within one working day. If it's urgent, you can also reach us via the contact page.
What Margins Does IngramSpark Require?
IngramSpark takes a simpler, uniform approach. The recommended minimum is 0.5″ (about 13 mm) on all four sides, with an optional inside margin of up to 1″ (25 mm) for extra spine safety on thick books. Unlike KDP, IngramSpark does not vary the gutter by page count; the same 0.5″ minimum applies whether the book is 100 pages or 600. The full specification lives in the IngramSpark File Creation Guide.
Because IngramSpark distributes through the Ingram network to a wide range of retailers and print facilities, slight trim variation across print sites is a real consideration. For any book over roughly 400 pages that will go out through IngramSpark, we default to a 0.75″ inside margin rather than the bare 0.5″ minimum; the extra safety costs nothing and absorbs the small differences between print locations.
Here is how the two platforms compare at a glance:
| Margin | Amazon KDP | IngramSpark |
|---|---|---|
| Inside (gutter) | 0.375″–0.875″, scaled by page count | 0.5″ flat (1″ optional for thick books) |
| Outside | 0.25″ min (0.375″ with bleed) | 0.5″ recommended |
| Top | 0.25″ min (0.375″ with bleed) | 0.5″ recommended |
| Bottom | 0.25″ min (0.375″ with bleed) | 0.5″ recommended |
| Bleed allowance | 0.125″ beyond trim | 0.125″ beyond trim |
How Do You Set Mirror Margins in Microsoft Word?
For a print book you need mirror margins, where the inside and outside margins swap sides between left and right pages, exactly as in a bound book. Word does not do this by default. The process:
- Go to Layout (or Page Layout in older versions) → Margins → Custom Margins.
- In the Multiple pages dropdown, select Mirror margins. The “Left” and “Right” fields change to “Inside” and “Outside”.
- Set the Inside margin to the correct gutter value for your page count and platform.
- Set Outside, Top, and Bottom to at least the platform minimums.
- Click OK and apply to the whole document.
Before you touch the margins, make sure Word’s page size matches your book’s trim size. Go to Layout → Size → More Paper Sizes and enter your trim dimensions (common sizes are 5″ × 8″, 5.5″ × 8.5″, and 6″ × 9″). Margins are calculated relative to page size, so this step has to come first. If you would rather start from a correct file, KDP offers free Word manuscript templates pre-set with the right dimensions and margins for each trim size, which removes one whole source of error.
Apply the margin change to the whole document rather than a single section, or Word will silently leave front-matter and chapter-opening sections on the old settings. After you apply, switch to a two-page spread view (View → Multiple Pages) and scroll through: the wider inside margins should meet in the centre of each spread, mirrored left and right. If both pages of a spread look identical, mirror margins did not take, and the file is not print-ready.
What Margin Mistakes Cause Print-on-Demand Rejection?
The most frequent margin-related rejection on both KDP and IngramSpark is an insufficient gutter: either a flat margin value chosen without accounting for page count, or mirror margins left switched off so the binding side never gets its extra space. With standard (non-mirrored) margins, both sides of every spread are identical, and the spine edge is starved.
The next most common error is leaving Word’s page size at the default 8.5″ × 11″ while working in a 6″ × 9″ trim; the numbers in the margin dialog look right, but they are being calculated against the wrong page, so the printed result is wrong. A third recurring problem is placing running headers or page numbers outside the margin boundary, which KDP’s automated preflight flags. When we audit a rejected file, one of these three accounts for the fault almost every time.
How Does Bleed Change Your Margins?
Bleed applies when any image, colour, or design element is meant to print right to the edge of the trimmed page. Most text-only interiors do not need it. If yours does, for example a cookbook with full-page photos or a children’s book with full-colour backgrounds, the outside, top, and bottom minimums on KDP rise to 0.375″, and you add 0.125″ of bleed beyond the trim on every edge.
IngramSpark handles bleed the same way: bleed elements extend 0.125″ past the trim, and all live content (text, logos, anything that must not be cut) sits at least 0.125″ inside the trim edge. On both platforms the inside margin stays at its standard minimum regardless of bleed, because the spine edge is never a bleed edge.
What Margin Settings Should You Start With?
For working defaults that clear both KDP and IngramSpark for a standard novel-length paperback (200–300 pages) in a 6″ × 9″ trim, these are a reliable starting point:
- Inside (gutter): 0.75″, comfortably above both platforms and safe near the 300-page threshold
- Outside: 0.5″
- Top: 0.75″
- Bottom: 0.75″
These give a reading-friendly text block with enough safety to absorb minor trim variation. Once you know your final page count and platform, you can tighten or adjust, but starting here clears the most common rejection reasons before you submit. If your interior carries images, pair these margins with correct interior font sizing so the text block stays balanced on the page.
Frequently Asked Questions
Do KDP and IngramSpark use the same margin requirements?
No. KDP scales the inside (gutter) margin by page count, from 0.375″ up to 0.875″, and sets outside, top, and bottom minimums of 0.25″. IngramSpark uses a flat 0.5″ recommendation on all four sides regardless of page count. If you publish to both, set your margins to satisfy the stricter of the two on each edge so a single file works everywhere.
What gutter margin do I need for a 400-page book?
On KDP, a 400-page book falls in the 301–500 range and needs a minimum 0.625″ gutter. On IngramSpark the minimum is 0.5″, though 0.75″ is a safer choice at that thickness. Using 0.75″ satisfies both platforms with a comfortable margin, so it is a sensible single value for a book of that length.
Do I need mirror margins for an ebook?
No. Mirror margins matter only for print, where left and right pages face each other across a spine. Ebooks are reflowable and have no fixed pages or binding, so margin settings do not carry over. Set mirror margins in your print file only; your ebook conversion ignores them.
Will Word warn me if my margins are too small?
Word may show a generic “margins are outside the printable area” notice tied to your desktop printer, but it does not know KDP or IngramSpark rules and will not flag an insufficient gutter for print-on-demand. The real check happens during each platform’s preflight after upload, so verify the values yourself against the page-count tier before you submit.
Does trim size change the margin requirements?
The minimum margins are the same across trim sizes; KDP’s gutter tiers and IngramSpark’s 0.5″ flat minimum do not vary with trim. What changes is how much text area remains: a smaller trim like 5″ × 8″ leaves a narrower text block after margins, so you may want a smaller body font or slightly tighter outside margins to keep lines readable.
