Spine width calculator
Your page count and your paper decide how thick the book is. Enter both to get the spine width and the full cover size, including bleed.
Spine width
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Full cover, with bleed
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Back cover, spine and front cover on one sheet, plus 0.125″ of bleed on every outer edge. This is the artboard size to give your designer.
Spine width at a glance
For the two stocks most paperbacks use. This table is built with the page, so it carries both units rather than following the toggle above.
| Pages | White (444 PPI) | Cream (400 PPI) |
|---|---|---|
| 100 | 5.7 mm · 0.225″ | 6.3 mm · 0.250″ |
| 150 | 8.6 mm · 0.338″ | 9.5 mm · 0.375″ |
| 200 | 11.4 mm · 0.450″ | 12.7 mm · 0.500″ |
| 250 | 14.3 mm · 0.563″ | 15.9 mm · 0.625″ |
| 300 | 17.2 mm · 0.676″ | 19.0 mm · 0.750″ |
| 350 | 20.0 mm · 0.788″ | 22.2 mm · 0.875″ |
| 400 | 22.9 mm · 0.901″ | 25.4 mm · 1.000″ |
| 500 | 28.6 mm · 1.126″ | 31.8 mm · 1.250″ |
| 600 | 34.3 mm · 1.351″ | 38.1 mm · 1.500″ |
Figures from Amazon KDP's printing specifications, read 9 August 2026. IngramSpark's stocks differ slightly; check your printer's own table before sending artwork to press.
Questions
- How do you calculate spine width?
- Divide the page count by the paper's pages-per-inch (PPI). KDP's white paper is 444 PPI and its cream is 400, so a 300-page book is 300 ÷ 444 = 0.676 inches on white, or 0.75 inches on cream. Note that page count means pages, not sheets: a 300-page book has 150 sheets of paper.
- Does the cover need to include bleed?
- Yes. A paperback cover is trimmed on all four outer edges, so KDP asks for 0.125 inches of bleed on each. That is different from the interior, where the binding edge is never trimmed and takes no allowance at all. The full cover width is therefore two trim widths, plus the spine, plus 0.25 inches of bleed.
- Why can't I put text on my spine?
- Below 100 pages the spine is too narrow to hold legible type, and both KDP and IngramSpark reject covers that put any there. If your book is close to the threshold, a slightly larger type size or more generous leading will push the page count over it — which is one of the things Nueel lets you change and see immediately.
- Is cream or white paper thicker?
- Cream. KDP's cream stock runs 400 pages to the inch against white's 444, so the same manuscript is about 11% thicker on cream. Cream is the conventional choice for novels because the lower contrast is easier on the eye over long stretches; white is usual for non-fiction and anything with images.
- Will my spine width change if I edit the book?
- Yes, and this is the trap. Spine width follows page count, and page count follows every typographic decision — the typeface, the size, the leading, the margins. Commission cover artwork before the interior is final and you will be paying for it twice. Settle the interior first, then read the final page count off it.
- Does this work for hardbacks?
- No. These figures are for perfect-bound paperbacks. A case-bound hardback adds board thickness and a hinge allowance, and the numbers come from your printer rather than from a formula.
The page count this depends on is one you control.
Typeface, size, leading and margins all move it. Nueel lets you change any of them and see the new page count immediately — then export a print-ready PDF at the trim you chose.