KDP paperback cover
KDP spine width calculator
Spine width is the page count times the thickness of one page. KDP publishes the factors: 0.002252 in per page for white paper, 0.0025 in for cream, 0.00235 in for groundwood, 0.002347 in for premium color and 0.002252 in for standard color. The full cover is the back, spine and front side by side, plus 0.125 in of bleed all round.
The numbers and the preview are free. The downloadable template, with bleed, spine, safe areas and barcode space marked at full size, is part of Pro.
Factors from Amazon KDP Help: Create a Paperback Cover and Paperback Submission Guidelines (groundwood). Last checked 7 October 2026.
Spine width by page count and paper
In inches, rounded to three decimals. Use the exact page count of your interior: KDP counts every page in the file, blank pages included, and rounds an odd count up to the next even number.
Standard color uses the same factor as white paper, and its minimum is 72 pages, so the first two rows don't apply to it.
| Pages | White | Cream | Groundwood | Standard color | Premium color |
|---|---|---|---|---|---|
| 24 | 0.054 | 0.060 | 0.056 | 0.054 | 0.056 |
| 48 | 0.108 | 0.120 | 0.113 | 0.108 | 0.113 |
| 80 | 0.180 | 0.200 | 0.188 | 0.180 | 0.188 |
| 100 | 0.225 | 0.250 | 0.235 | 0.225 | 0.235 |
| 150 | 0.338 | 0.375 | 0.352 | 0.338 | 0.352 |
| 200 | 0.450 | 0.500 | 0.470 | 0.450 | 0.469 |
| 300 | 0.676 | 0.750 | 0.705 | 0.676 | 0.704 |
Full cover size
KDP's formulas:
Cover width = 0.125 + back width + spine + front width + 0.125Cover height = 0.125 + trim height + 0.125
Worked example: an 8.5 × 11 in coloring book with 50 designs on blank backs has 100 pages. On white paper the spine is 100 × 0.002252 = 0.2252 in, so the cover is 0.125 + 8.5 + 0.2252 + 8.5 + 0.125 = 17.475 × 11.25 in, or 5243 × 3375 pixels at 300 dpi.
The cover is always one PDF with back, spine and front together, and every cover has bleed, even when the interior doesn't.
The 79-page rule for spine text
KDP only allows text on the spine from 79 pages. Below that, a cover with spine text is rejected; keep the spine to a color or a pattern. KDP's wording differs slightly between pages: the cover guide says “at least 79 pages”, the submission guidelines say “more than 79”, and its Cover Creator needs 80. A book of 80 pages or more is safe under all three.
When text is allowed, keep 0.0625 in between the text and each spine fold. KDP also allows for 0.0625 in of variance either side of the fold lines, so avoid hard edges or thin borders right on a fold.
With blank backs, a coloring book reaches 80 pages at 40 designs.
Barcode and safe areas
KDP adds a barcode to the back cover if you don't supply one. Leave room for it: KDP's suggested barcode size is 2 × 1.2 in on a white background, at least 0.25 in from the spine and the trim. Keep front and back cover text at least 0.125 in inside the trim lines, and out of the spine area.
Barcode rules: KDP Barcodes, checked 7 October 2026.
Groundwood paper
Groundwood is a lighter (45 lb), lower-cost paper for black-and-white interiors; KDP puts its per-page printing cost about 5% below white and cream. Per page it is slightly thicker than white and thinner than cream: KDP's submission guidelines give 0.00235 in. If you switch an existing book to groundwood, KDP warns that books over 350 pages (from cream) or 525 pages (from white) need a new spine size on the cover.
Source: KDP Groundwood Paper.
Get the page count right first
The spine is only as accurate as the page count. The KDP coloring book interior maker counts your designs, blank backs, front pages and the final even page, and fills the cover calculator for you. For the interior side of the same book, see the bleed and margins calculator.
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