Trim and gutter, checked
Pick from 17 common KDP and IngramSpark trims. Bookshaper flags a gutter below KDP's minimum for your page count.
KDP book formatting
KDP book formatting software, with a free spine calculator.
Work out your trim, gutter and spine width below, free. Then format the interior, the ebook and the cover wrap to match, in one app.
Free trial, 7 days of actual use. Then $29.99 once for Windows, macOS and Linux.
Free calculator
Trim size, gutter and spine width for KDP.
No account, no AI, no credits. Pick a trim, enter a page count, and choose your paper.
Your print specs
- Trim
- 5.5″ × 8.5″ (140 × 216 mm)KDP + IngramSpark
- Minimum gutter, KDP
- 0.500″ (12.7 mm)Inside margin for 300 pages. KDP's minimum rises with page count.
- Minimum gutter, IngramSpark
- 0.500″ (12.7 mm)IngramSpark publishes one flat minimum.
- Spine width, KDP
- 0.750″ (19.0 mm)Long enough for spine text.
- Full cover wrap, KDP
- 12.000″ (304.8 mm) × 8.750″ (222.3 mm)Back, spine and front, with 0.125″ bleed on the outside edges.
Figures follow KDP's published paperback specifications. Check your final files against KDP's own previewer before you publish.
Rather have your cover and interior sized for you?
Bookshaper can do that. It takes the page count from your typeset interior, works out the spine, sizes the cover wrap to match, and checks the interior against KDP's specifications before you export.
Interior
A KDP-ready interior without the guesswork.
The app checks your interior against the same numbers the calculator shows.
Preflight before export
A report checks the interior against KDP and IngramSpark specifications before you upload anything.
Page-level fix-its
Guided fixes for widows, orphans, hyphen ladders and overflowing lines in the print layout.
62 book templates
Genre and era templates across nine categories, adjustable down to fonts, headings and scene breaks.
Professional typesetting
Character-level justification and hung punctuation in the print-ready PDF.
Ebook from the same file
Export EPUB for Kindle and other stores from the manuscript you formatted for print.
Cover
A cover wrap sized to your spine.
Cover Studio exports a full wrap PDF for KDP, with the spine width worked out from your page count and paper, and checks how the front reads at Amazon thumbnail size.
Wrap PDF for KDP
Back, spine and front with bleed, sized from your interior. IngramSpark and custom templates are supported too.
Thumbnail test
See the front cover at Amazon search size, with print safe-area guides.
Imports your manuscript
Bring a DOCX, EPUB, HTML or Markdown file and Bookshaper keeps its chapters.
The short version
Questions, answered.
How do I calculate my KDP spine width?+
Multiply your interior page count by the paper thickness KDP publishes for your paper and ink. The calculator on this page does it for every KDP paper type, and adds the full cover wrap size with bleed.
What gutter does KDP require?+
KDP's minimum inside margin grows with page count, from 0.375 inches for short books to 0.875 inches for the longest. Enter your page count above to see yours.
Which trim sizes does KDP support?+
KDP supports a set list of paperback trims, with 6 by 9 inches the most common for fiction. The calculator lists 17 common trims and flags any that KDP does not offer.
Does Bookshaper export files KDP accepts?+
Yes. Bookshaper exports a print-ready PDF interior at your trim size, an EPUB for Kindle, and a full cover wrap PDF sized to your page count. A preflight report checks the interior against KDP's specifications before you export.
Does the calculator use AI or cost anything?+
No. It runs in your browser from the same formulas the Bookshaper app uses, with no account, no AI and no credits.
How much does Bookshaper cost?+
$29.99 one-time at launch pricing, through December 31, 2026, for Windows, macOS and Linux on one license. The free trial runs for 7 days of actual use.
Try it on your own manuscript.
7 days of actual use, not 7 calendar days. Buy once when you are ready; one license covers Windows, macOS, and Linux.