Free tool
Book cover calculator for KDP paperbacks.
Choose a trim size, ink and paper, and enter the page count. The calculator gives you the spine width, the full cover size with bleed in inches, millimetres and pixels, and the interior margins Amazon KDP asks for.
On Amazon KDP, a paperback's spine width is its page count multiplied by the thickness of one page — 0.002252″ for black & white on white paper, 0.0025″ on cream. The full cover is two trim widths plus the spine, with 0.125″ of bleed on every outer edge: a 6″ × 9″ book of 200 pages in black & white on white paper needs a cover file of 12.700″ × 9.250″.
Your book
Cover file
Spine width
0.450″
11.4 mm
- Full cover, with bleed
- 12.700″ × 9.250″322.6 × 235.0 mm
- At 300 dpi
- 3,810 × 2,775 px
- Bleed, on each outer edge
- 0.125″3.2 mm
- Spine starts
- 6.125″ from the left edge
- Text on the spine
- Possible
Interior margins
- Inside margin (gutter)
- at least 0.5″12.7 mm
- Outside, top and bottom
- at least 0.25″0.375″ if the interior bleeds
Estimates based on Amazon KDP's published specifications. Amazon updates them from time to time, so check the final numbers against KDP's own cover calculator before you upload.
How the numbers are worked out
These figures follow Amazon KDP's published specifications, which Amazon updates from time to time. Check them against KDP before you upload.
How is the spine width of a paperback calculated?
Multiply the interior page count by the thickness of one page. Amazon KDP uses 0.002252″ per page for black & white on white paper, 0.0025″ on cream paper, 0.002252″ for standard colour and 0.002347″ for premium colour. A 200-page book in black & white on white paper has a spine of 0.450″ (11.4 mm).
How big is the full cover file?
The width is the back cover, spine and front cover side by side — two trim widths plus the spine — plus 0.125″ of bleed on the left and on the right. The height is the trim height plus 0.125″ at the top and at the bottom. A 6″ × 9″ book of 200 pages in black & white on white paper needs 12.700″ × 9.250″, or 3,810 × 2,775 px at the 300 dpi KDP asks for.
Can I put text on the spine?
Only from 100 pages. Below that, KDP does not print text on the spine, so the cover has to work without it.
How many pages can a KDP paperback have?
Between 24 and 828. That is the widest range, for black & white on white paper.
What inside margin (gutter) does the interior need?
It grows with the page count: 0.375″ up to 150 pages, 0.5″ up to 300 pages, 0.625″ up to 500 pages, 0.75″ up to 700 pages, and 0.875″ up to 828 pages. The outside, top and bottom margins need at least 0.25″, or 0.375″ if the interior bleeds.
Rather not do the cover yourself?
Every Bookspert package includes custom cover design and Amazon publishing. We design the cover and the interior, format the eBook and publish the book for you.