How to fix your book's margins

Margin errors mean something on your pages sits too close to an edge or to the spine fold. The fix is the right numbers for your printer and page count, set once in your master layout.

Quick answer

For KDP, use at least 0.25" outside, top and bottom (0.375" with bleed) and an inside margin from 0.375" (up to 150 pages) to 0.875" (701+ pages). For IngramSpark, keep everything at least 0.5" from every edge. Page numbers and headers count.

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KDP inside margin (gutter) by page count

Pages	Inside margin (minimum)	Outside, top, bottom (minimum)
24 to 150	0.375"	0.25" (0.375" with bleed)
151 to 300	0.5"	0.25" (0.375" with bleed)
301 to 500	0.625"	0.25" (0.375" with bleed)
501 to 700	0.75"	0.25" (0.375" with bleed)
701 to 828	0.875"	0.25" (0.375" with bleed)

IngramSpark: 0.5" (13 mm) from every trim edge for all text, page numbers, borders and anything important. For thick books, add more on the inside so words don't vanish into the fold.

Our advice: minimums are minimums. 0.75" outside and 0.75" to 1" inside looks better and passes every printer. Use the free margin calculator to get your numbers.

Fix it in Word

Layout → Margins → Custom Margins.
Under Pages, set Multiple pages to Mirror margins. Now "Left/Right" become "Inside/Outside".
Type your Inside, Outside, Top and Bottom numbers. Leave Gutter at 0 (you already put the extra on the Inside).
Set Apply to: Whole document. Section breaks can hide old margins in later chapters otherwise.
Layout tab of the same box: set Header and Footer "From edge" to at least your printer's minimum (0.5" for IngramSpark), so page numbers sit inside the safe area.

Fix it in InDesign or Affinity

Go to your master / parent pages (not individual pages).
InDesign: Layout → Margins and Columns. Affinity: Document → Margins. Set Inside and Outside.
Check that page number and running header frames sit inside the new margins on the master.
Check any page that has its own override (chapter openers, full-page images).

Why margin errors come back

Your page count grew past a KDP step (for example from 148 to 156 pages), so the inside margin needs to grow too.
The PDF isn't your trim size. If it's letter size, the printer shrinks it and your margins move. Fix page size first.
Page numbers in the footer sit below the safe line even though the body text is fine.
A wide table or picture pokes past the margin on one page.

Want every click spelled out? Read the full walkthrough: KDP margin error and the gutter table on sparkprep.legenddary.com.

Want every click spelled out? Read the full walkthrough: IngramSpark "outside the safety area" error on sparkprep.legenddary.com.

Find out what's wrong with your files before the printer does

SparkPrep checks your cover and every interior page against the exact rules Amazon KDP, IngramSpark, Barnes & Noble Press and Lulu use, tells you each problem in plain English, and can fix it for you.

Scan my book free See how SparkPrep works

The scan is free and shows how many problems your files have. To see every problem and where it is, the audit is $1.99 ($3.99 after January 1). The Advanced Audit checks every page, up to 300, for $9.99.

Questions people ask

What is the gutter in a book?

The inside margin by the spine. Thicker books curve more there, so they need a bigger gutter.

Do page numbers have to be inside the margins?

Yes. KDP and IngramSpark treat page numbers and headers like any other content.

More on this site

Fix your book's print filesPlain-English fixes for the book file problems printers reject: bleed, margins, fonts, transparency, low-resolution pictures, color, ink, page size and spine.How to add bleedHow to add 0.125 inch bleed to a book cover or interior in Canva, InDesign, Affinity or Word, how to check it, and why bleed errors come back.Fix PDF page sizeIf your interior PDF is letter size but your book is 6x9, the printer shrinks or crops it. How to set the right trim size in Word and InDesign.How to embed fontsFix 'font not embedded' and font license errors in your book PDF: how to embed every font in Word, InDesign, Affinity and Canva, and how to check in Acrobat.How to flatten transparencyShadows and see-through shapes can print as boxes. How to flatten transparency and layers for KDP and IngramSpark in Canva, InDesign, Affinity and Acrobat.Fix low-resolution picturesHow to fix low-resolution (under 300 DPI) pictures in a book: pixel sizes for common covers and pages, how to stop Word compressing images, and what not to do.Fix color and ink coverageFix 'ink coverage exceeds 240%' and 'RGB found' errors: convert book files to CMYK or true grayscale and lower total ink in Acrobat, InDesign and Canva.Fix spine width and spine textFix a wrong spine width or spine text error: how to re-fit your cover for a new page count or paper, center spine text and know when spine text is allowed.

Free help from SparkPrep

Book Preflight, ExplainedWhat book preflight is, who needs it and what gets checked before KDP or IngramSpark prints your book.Print Cover SizesFull cover size charts, spine widths, barcode space and hardcover rules for KDP and IngramSpark.Rejection Messages DecodedWhat KDP and IngramSpark rejection messages really mean, in plain English, and what to do next.First Book GuideYour first print book, step by step: costs, timeline, words to know and the mistakes to skip.Free book toolsCover calculator, spine width, margins, DPI checker and page count, on sparkprep.legenddary.com.

Last updated 2026-11-01. Written by Joshua Davis, founder of SparkPrep. Numbers come from each printer's own published guides; always double-check your printer's current rules before you upload.