Print Tools
Book Spine Width Calculator
Calculate spine width from page count and paper stock.
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What this tool does
Enter your page count and choose a paper stock to estimate the book's spine width in millimetres and inches, so you can set up a cover template that lines up with the printed block.
Settings
Book details
Interior paper
Result
Estimated spine width
10 mm
0.394 inches · 100 sheets
Estimate for a paperback. Confirm the exact spine with your printer before finalising the cover.
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Size your book spine before designing the cover
A wrap-around book cover needs the spine width to be exactly right, or the front and back artwork will creep onto the spine or leave gaps. Spine width depends on two things: how many pages the book has, and how thick each sheet of paper is. This calculator multiplies the number of leaves by the paper thickness to estimate the spine in millimetres and inches.
Enter the page count, pick the closest paper stock, and read the spine width. Use it to set the spine panel in your cover template before you send files to a printer or print-on-demand service.
How spine width is calculated
Two printed pages share one sheet of paper (a leaf). So the number of leaves is the page count divided by two, and the spine width is that many leaves multiplied by the thickness of one sheet. Heavier and bulkier papers make a thicker spine for the same page count.
- 80 gsm office/text — about 0.10 mm per sheet.
- 90 gsm — about 0.11 mm per sheet.
- 100 gsm coated — about 0.12 mm per sheet.
- 120 gsm — about 0.15 mm per sheet.
- Cream novel bulky 80 gsm — about 0.13 mm per sheet.
How to use it
- Enter the total page count (count every page, including blanks).
- Choose the paper stock that matches your interior pages.
- Read the spine width in mm and inches.
- Add it to your cover template as the spine panel width between the front and back.
Notes and limitations
- This estimates a paperback (perfect-bound or saddle-stitched) spine. Hardcover spines add board and case thickness — check your binder's spec.
- Paper thickness varies by mill and finish; if your printer publishes a pages-per-inch (PPI) or caliper figure, use that for exact results.
- Always confirm the final spine width with your print provider before going to press; many supply their own spine calculator for their exact stock.
FAQs
Quick answers
How do I find the spine width of my book?
Divide the page count by two to get the number of sheets, then multiply by the paper's per-sheet thickness. This calculator does that for common stocks and shows the result in mm and inches.
Does the cover paper affect the spine?
For a paperback the spine width is driven by the interior pages. The cover stock wraps around but adds very little. Hardcovers are different — the case boards add several millimetres.
Why does my printer's number differ slightly?
Paper thickness varies by brand and finish. Printers measure their actual stock (often quoted as pages-per-inch). Use their figure for the final template; this tool gives a close estimate.
Do blank pages count?
Yes. Count every physical page in the book, including blanks at the start and end, because they all add to the thickness.
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