- Spine
- 0.6756″17.16 mm
- Cover wrap
- 12.9256″× 9.25″
- Interior + bleed
- 6.1250″× 9.25″
- Spine text
- allowedfrom 80 pp
300 pages · 6 × 9 · White paper · rates checked 2026-11-10 · check on KDP ↗
Amazon KDP · Print · Rates 2026-11
Book spine width calculator — exact spine and cover wrap size
300 pages on white paper is a 0.6756″ (17.16 mm) spine, and the full cover wrap for a 6×9 book is 12.9256″ × 9.25″. Change page count, paper or trim below and every number moves with it — spine, cover, and the interior size with bleed.
Spine width · 6 × 9 · White paper
0.6756in
Spine text allowed — 80 pages is the minimum
6 × 9 · 300 pages · 0.6756″ / 17.16 mm · cover 12.9256″ × 9.25″ · interior with bleed 6.125″ × 9.25″ · Cover and spine sizes ↗ / Trim, bleed and margins ↗
- Cover width
- 12.93 in
- Cover height
- 9.25 in
- Spine text from
- 80 pp
Your book
24–828
Drag through the page range
Spine = pages × paper thickness (0.002252″ white, 0.0025″ cream). Cover wrap = 0.125″ bleed + back + spine + front + 0.125″ bleed. Rates 2026-11, checked 2026-11-10.
Every trim, every paper
Spine width, cover wrap and interior size
Spine width depends on page count and paper thickness only — the trim changes how much cover sits either side of it. Both are below, in the unit you picked.
- Spine at 24 pp
- 0.0540″
- Spine at 828 pp
- 1.8647″
- White paper, per page
- 0.002252″
- Spine text from
- 80 pages
the shortest KDP paperback
the 828-page ceiling
cream 0.0025″
79 pages = 0.1779″
Spine width by page count and paper
in inches
| Pages | White | Cream | Groundwood | Colour |
|---|---|---|---|---|
| 24 pp | 0.0540″ | 0.0600″ | 0.0564″ | 0.0563″ |
| 50 pp | 0.1126″ | 0.1250″ | 0.1175″ | 0.1174″ |
| 80 pp | 0.1802″ | 0.2000″ | 0.1880″ | 0.1878″ |
| 100 pp | 0.2252″ | 0.2500″ | 0.2350″ | 0.2347″ |
| 150 pp | 0.3378″ | 0.3750″ | 0.3525″ | 0.3521″ |
| 200 pp | 0.4504″ | 0.5000″ | 0.4700″ | 0.4694″ |
| 300 pp | 0.6756″ | 0.7500″ | 0.7050″ | 0.7041″ |
| 400 pp | 0.9008″ | 1.0000″ | 0.9400″ | 0.9388″ |
| 500 pp | 1.1260″ | 1.2500″ | 1.1750″ | 1.1735″ |
| 700 pp | 1.5764″ | 1.7500″ | 1.6450″ | 1.6429″ |
| 828 pp | 1.8647″ | 2.0700″ | 1.9458″ | 1.9433″ |
Page count × paper thickness, rounded to four decimals. KDP rounds the page count up to an even number first.
Full cover wrap for all eight trims
300 pages · White paper · inches
| Trim | Spine | Cover W × H | Interior + bleed | Large |
|---|---|---|---|---|
| 5 × 8 | 0.6756″ | 10.9256″ × 8.25″ | 5.1250″ × 8.25″ | no |
| 5.25 × 8 | 0.6756″ | 11.4256″ × 8.25″ | 5.3750″ × 8.25″ | no |
| 5.5 × 8.5 | 0.6756″ | 11.9256″ × 8.75″ | 5.6250″ × 8.75″ | no |
| 6 × 9 | 0.6756″ | 12.9256″ × 9.25″ | 6.1250″ × 9.25″ | no |
| 7 × 10 | 0.6756″ | 14.9256″ × 10.25″ | 7.1250″ × 10.25″ | yes |
| 8 × 10 | 0.6756″ | 16.9256″ × 10.25″ | 8.1250″ × 10.25″ | yes |
| 8.5 × 8.5 | 0.6756″ | 17.9256″ × 8.75″ | 8.6250″ × 8.75″ | yes |
| 8.5 × 11 | 0.6756″ | 17.9256″ × 11.25″ | 8.6250″ × 11.25″ | yes |
Large trim means wider than 6.12″ or taller than 9″, which raises the per-page printing cost.
What moves the spine — and what does not
Page count and paper thickness. Nothing else. The same 300 pages is 0.6756″ on white paper at every one of the eight trim sizes, because the spine is the stack of paper, not the face of the book. Cream paper reads 0.7500″ — 0.0025 in per page against 0.002252 in — so switching paper on a 300-page book widens the spine and changes the cover file, without touching the interior layout.
Spine text starts at 80 pages
79 pages gives a 0.1779″ spine and KDP rejects a file with text on it; 80 pages gives 0.1802″ and it is allowed. Keep the text at least 0.125 in clear of both spine folds and leave a safety margin top and bottom — the folds move by a fraction of a millimetre in production, and a design that touches the fold shows it.
Where the 0.125″ bleed goes
A 6×9 cover file is 0.125 + 6 + spine + 6 + 0.125 wide and 9 + 0.25 tall: at 300 pages that is 12.9256 × 9.25 in. The interior only needs bleed when artwork runs to the edge — then it becomes 6.125 × 9.250 in, and your outside margin grows from 0.25″ to 0.375″ to keep the text off the trim.
Why the fourth decimal matters
0.6756″ rounded to 0.68″ moves 0.0044″, and the error lands twice — once at each fold — so the artwork shifts against the spine text. A 0.02″ slip is half a millimetre and shows on a dark spine. Build the cover from four decimals; if the page count is still an estimate, 300 pages is about 90,000 words at 6×9.
A thicker book costs more to print and sits differently on the shelf: every extra page adds to both the spine and the per-page rate. Work out the printing cost once you know the final page count, then check the royalty at the price you plan to charge.
Rates 2026-11, checked 2026-11-10 · Cover and spine sizes ↗ / Trim, bleed and margins ↗
Questions
Spine and cover questions people actually ask
0.6756 in (17.16 mm) on white paper, 0.7500 in (19.05 mm) on cream. Paper is the only thing that moves it — trim size does not.
Page count × paper thickness: white is 0.002252 in per page, cream 0.0025. So 300 pages is 300 × 0.002252 = 0.6756 in.
White 0.002252 in, cream 0.0025 in, groundwood 0.00235 in, colour 0.002347 in per page. Cream is thickest, so a cream book of the same page count has the wider spine.
0.125 + 6 + spine + 6 + 0.125 wide and 9 + 0.25 tall. At 300 pages: 12.9256 × 9.25 in on white, 13.0000 × 9.25 in on cream. Interior with bleed: 6.125 × 9.250 in.
Yes — 0.125 in on all four sides, already in every number here. The interior only needs bleed if artwork runs to the edge; the outside margin then grows from 0.25 in to 0.375 in.
KDP only allows spine text from 80 pages: 0.1779 in is rejected, 0.1802 in is allowed. Keep text 0.125 in clear of both folds.
Its help pages use inches with a decimal and its templates publish both. This tool defaults to inches and switches to millimetres from the same numbers, so nothing drifts.
Next numbers to work out
A spine is one file. The cost of the pages behind it is the next number to pin down.