How is KDP spine width calculated?

For paperbacks, spine width = (page count × paper thickness per page) + 0.06 inches for the cover. White paper is 0.002252" per page, cream is 0.0025", and standard color is 0.002252". For hardcovers, the formula is (page count × 0.00226) + 0.187" for board thickness — no cover offset is added.

When can I add text to the spine?

Amazon KDP requires at least 79 pages before spine text is allowed. The spine must also be at least 0.35" wide. Below that, the spine must remain blank — any text or graphics will cause your cover to be rejected.

What trim sizes does KDP support?

KDP supports 17 paperback trim sizes ranging from 5"×8" to 8.5"×11". Hardcover (case laminate) supports 6 trim sizes: 5.5"×8.5", 6"×9", 6.14"×9.21", 6.69"×9.61", 7"×10", and 8.25"×11". The most popular sizes are 6"×9" and 5.5"×8.5".

What's the difference between white and cream paper?

White paper (0.002252" per page) produces a thinner spine and is standard for most books. Cream paper (0.0025" per page) is slightly thicker, giving the book a more substantial feel — popular for novels and literary fiction. Cream paper is only available with black-and-white ink.

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KDP Spine Width Calculator

Get exact spine width and full cover dimensions for your Amazon KDP book. Uses Amazon's official formulas for paperback and hardcover.

Book Details

Binding Type

Trim Size

Page Count

Must be even. Min 24 pages.

Paper Type

Cover Dimensions

Spine Width

0.3978"

10.10 mm · 119 px @ 300 DPI

Full Cover Width

12.648"

3794 px

Full Cover Height

9.250"

2775 px

Bleed / Wrap

0.125" per side

Spine text is allowed at this page count.

How KDP Cover Layout Works

Back Cover

Spine

0.398"

Front Cover

Total: 12.648" × 9.250"

KDP Spine Width Formulas

Paperback

spine = (pages × paper_factor) + 0.06"

White paper: 0.002252" per page
Cream paper: 0.0025" per page
Color paper: 0.002252" per page

Hardcover (Case Laminate)

spine = (pages × 0.00226) + 0.187"

0.187" accounts for board thickness
Paper type is always white for HC
Min 75 pages required

Frequently Asked Questions

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