KDP Spine Width Calculator

Your spine width is the page count times the thickness of one page, and that thickness depends on the paper. Enter yours to get the spine in inches, millimeters and pixels, and to see whether KDP lets you print text on it.

Numbers from KDP's help pages, checked 2026-11-13. Paperback.

Trim sizeInk and paperInterior page count(KDP rounds odd counts up)

Spine = pages × 0.002252 in. Cover = bleed + back + spine + front + bleed, with 0.125 in bleed on every edge.

Spine width

0.2702 in

6.9 mm · 81 px at 300 DPI

Spine text

Allowed

KDP needs 79+ pages

Full cover

12.52 × 9.25 in

3756 × 2775 px

Trim line (0.125 in bleed outside it)Keep text inside (0.125 in from trim)Spine: text needs 0.0625 in clearance each sideBarcode area 2 × 1.2 in

Real size in inches, with trim, bleed, spine, safe-zone and barcode guides. Open it in Canva, Affinity, Illustrator or Inkscape.

Spine thickness per page

These are KDP's published values for one page of each paper type:

Pages	B&W, white	B&W, cream	B&W, groundwood	Standard color	Premium color
Per page	0.002252 in	0.0025 in	0.00235 in	0.002252 in	0.002347 in
24	0.054 in	0.060 in	0.056 in	-	0.056 in
50	0.113 in	0.125 in	0.118 in	-	0.117 in
80	0.180 in	0.200 in	0.188 in	0.180 in	0.188 in
100	0.225 in	0.250 in	0.235 in	0.225 in	0.235 in
150	0.338 in	0.375 in	0.353 in	0.338 in	0.352 in
200	0.450 in	0.500 in	0.470 in	0.450 in	0.469 in
300	0.676 in	0.750 in	0.705 in	0.676 in	0.704 in
500	1.126 in	1.250 in	1.175 in	1.126 in	1.173 in

Standard color starts at 72 pages. KDP's cover page gives standard color the same thickness as white paper (0.002252 in); its submission guidelines list 0.002347 in for all color paper. We use the cover page value, the difference is under 0.03 in on a 300-page book.

When can you print text on the spine?

KDP only allows spine text from 79 pages up (in practice 80, since page counts are even). Below that the spine is too thin and the text could wrap onto the front or back. When you do add text, leave 0.0625 in of clearance on each side: the fold can move slightly during binding.

Need the whole cover, not only the spine? Use the cover size calculator.

Questions

›How do I calculate KDP spine width?

Multiply the page count by the paper thickness: 0.002252 in for white paper, 0.0025 in for cream, 0.00235 in for groundwood and 0.002347 in for premium color.

›How many pages do I need for spine text on KDP?

At least 79 pages. Because KDP rounds page counts up to an even number, that means 80 pages in practice.

›Is cream paper thicker than white?

Yes. Cream adds 0.0025 in per page against 0.002252 in for white, so a 300-page book is about 0.07 in thicker on cream.

Sources (checked 2026-11-13)

Paperback Submission Guidelines: Trim sizes with page-count limits per paper type, spine width per page.
Create a Paperback Cover: Cover size formula, spine text minimum, spine clearance, barcode area.