KDP Spine Width and Cover Size: How to Calculate
Calculate your spine width and the exact full-cover size for your KDP paperback – formula, example and a free calculator.
Your KDP paperback cover is one PDF: back, spine and front side by side, with bleed all round. You need two numbers: spine width and full size.
Spine width
Spine width = page count × paper thickness
- Cream (black & white): 0.0025 in per page
- White (black & white) and standard colour: 0.002252 in per page
- Premium colour: 0.002347 in per page
Example: 284 pages on cream paper = 284 × 0.0025 = 0.71 in.
Full cover size
Width = bleed + back + spine + front + bleed Height = bleed + trim height + bleed (bleed is 0.125 in)
Example, 6 × 9 in, 284 pages, cream: width 0.125 + 6 + 0.71 + 6 + 0.125 = 12.96 in, height 9.25 in.
The quickest way: our free KDP spine calculator.
Spine text
KDP only allows spine text from 80 pages. Keep at least 0.0625 in from both spine edges.
More rules
- Safe area: important text at least 0.125 in inside the trim line
- Barcode: keep a 2 × 1.2 in area free at the lower right of the back cover
- Images: at least 300 dpi at print size
When the page count changes
The spine changes – and the whole cover must follow. In Papyrus Peak the cover editor is linked to your book: when the page count changes, spine, back and front move automatically, with guides for bleed, spine, safe areas and the barcode box.