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KDP cover size & spine width calculator
Exact cover dimensions for Amazon KDP paperbacks and hardcovers — spine width, full-wrap size, bleed, and spine-text rules, in inches and millimeters. Verified against KDP’s official cover calculator.
Full cover size
12.926″ × 9.250″
328.3 mm × 234.9 mm
Spine width
0.676″
17.2 mm
Spine text
Allowed
keep it 0.0625″ inside the spine edges
Layout, left to right: bleed 0.125″ · back cover 6″ · spine 0.676″ · front cover 6″ · bleed 0.125″. Height includes 0.125″ bleed top and bottom. Keep text and logos at least 0.25″ inside the trim edge, and leave the 2″ × 1.2″ barcode zone in the lower right of the back cover clear.
Or skip the math entirely.
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How the formulas work
Paperback:your cover is one flat sheet — back cover, spine, front cover — plus 0.125″ of bleed on every outside edge. The spine grows with your page count: each sheet of white paper adds 0.002252″, cream 0.0025″, premium color 0.002347″. That’s why you must finalize your interior before designing the cover: adding even a few pages changes the spine and shifts everything.
Hardcover (case laminate): the printed sheet wraps around rigid boards, so the file adds a 0.591″ wrap on every edge (glued inside the case), a 0.197″ hinge groove either side of the spine, 0.236″ of board overhang on the height, and a 0.189″ board allowance inside the spine width. KDP offers hardcover for books of 76 to 550 pages, in five trim sizes.
These numbers come straight from KDP’s own cover calculator — we verified the formulas against it at multiple page counts rather than copying the (often contradictory) numbers floating around the web.
Common questions
How is KDP spine width calculated?＋
Multiply your page count by the per-page paper thickness: 0.002252″ for black & white on white paper, 0.0025″ for cream paper, and 0.002347″ for premium color. Hardcovers add a 0.189″ board allowance on top of the page-block thickness.
What size should my KDP paperback cover PDF be?＋
Full width = 0.25″ of bleed + two trim widths + the spine; full height = trim height + 0.25″ of bleed. For a 6″×9″ book with 300 cream pages that's 12.25″ + 0.75″ spine = 13″ wide by 9.25″ tall.
How is a hardcover (case laminate) cover different from a paperback?＋
Hardcover files add a 0.591″ wrap that folds around the boards on every edge, a 0.197″ hinge either side of the spine, and 0.236″ of board overhang on the height — so the file is much larger than two trim widths. KDP hardcovers must be 76–550 pages.
When can I put text on the spine?＋
KDP only prints spine text when the spine is at least 0.0625″ wide — roughly 80+ pages for a paperback. Keep spine text at least 0.0625″ away from the spine edges so it can't wrap onto the covers.
Why was my KDP cover rejected for wrong dimensions?＋
Usually the spine width was computed for the wrong page count or paper type, the bleed is missing, or the file was exported at the trim size instead of the full-wrap size. Recalculate after any change to your interior — even one page changes the spine.