The formula
Spine width = page count × thickness of one page. Full cover width = bleed + back + spine + front + bleed. Full cover height = bleed + trim height + bleed.
Paper thickness is not a universal standard. The built-in presets are Amazon KDP's published paperback values; for any other printer, enter their thickness per page or their "PPI" (pages per inch). Always compare with your printer's own template before sending.
Hardcover case wraps and dust jackets add hinge and wrap allowances that differ by printer; they are not calculated here.
FAQ
- How wide is the spine of a 200-page book?
- With Amazon KDP's white paper value (0.002252 in per page) it is 0.450 in (11.44 mm). Cream paper is thicker: 0.500 in. Other printers use other paper.
- Can I put text on the spine?
- Depends on the printer. Amazon KDP prints spine text only on books with more than 79 pages and asks for a 0.0625 in margin on each side of the text.
- What does PPI mean for paper?
- Printers often give paper thickness as PPI — pages per inch. A paper with 444 PPI means 444 pages make one inch, so one page is 1 ÷ 444 inch.