Skip to content
ColorCraft

Free KDP tools

KDP spine width & cover size calculator

Enter your interior page count, paper, and trim size to get the exact spine width and full cover dimensions for an Amazon KDP paperback — in inches, millimeters, and pixels at 300 DPI. It's free, needs no signup, and uses KDP's published paper thickness values: the same math ColorCraft's cover generator uses to build print-ready wraps.

KDP prints 24–828 pages on this paper.

Spine width
0.2252"
5.7 mm
Full cover with bleed
17.475" × 11.250"
443.9 mm × 285.8 mm
Pixels at 300 DPI
5,243 × 3,375 px
Includes 0.125" bleed on the top, bottom, and outside edges.
Spine text
Allowed
KDP only prints spine text on books with 80 pages or more.

Need the cover itself? ColorCraft builds the full wrap PDF at exactly these dimensions.

Make my cover

How KDP calculates spine width

A paperback's spine is as wide as its stack of pages. KDP publishes a thickness per page for each paper type, and the spine width is simply:

spine width = interior page count × paper thickness per page

KDP paper thickness per page and page counts
Paper and inkThickness per pagePage counts KDP prints
White paper, B&W interior0.002252"24–828
Cream paper, B&W interior0.0025"24–776
Premium color0.002347"24–828
Standard color0.002252"72–600

Use the page count of your finished interior PDF. KDP checks the cover against the interior you upload, so a cover built for a different page count will have the wrong spine.

How to work out the full cover size

KDP wants one flat image with the back cover, spine, and front cover side by side, plus 0.125" of bleed around the outside:

  • width = bleed + trim width + spine + trim width + bleed
  • height = bleed + trim height + bleed

Example: a 100-page, 8.5" × 11" coloring book on white paper has a 0.2252" spine, so the full cover is 0.125 + 8.5 + 0.2252 + 8.5 + 0.125 = 17.4752" wide and 11.250" tall — 5,243 × 3,375 pixels at 300 DPI.

Spine width for common page counts

Spine width in inches by page count and paper
PagesWhite paperCream paperSpine text?
240.0540"0.0600"No
500.1126"0.1250"No
750.1689"0.1875"No
1000.2252"0.2500"Yes
1200.2702"0.3000"Yes
1500.3378"0.3750"Yes
2000.4504"0.5000"Yes
3000.6756"0.7500"Yes

Cover mistakes that get flagged by KDP

  • Art that stops at the trim line. Backgrounds must run into the 0.125" bleed on every outside edge.
  • Spine text on a thin book. Under 80 pages, leave the spine blank. Above that, keep 0.0625" clear on each side.
  • Text in the barcode area. KDP prints the barcode on the lower right of the back cover — keep that area free of text and important art.
  • A page count that changed. Adding or removing interior pages changes the spine, so rebuild the cover after edits.

Spine width FAQ

Sources

Covers 15 standard KDP paperback trim sizes; A4 (8.27" × 11.69") is not included. Also see the KDP royalty calculator.