Free tool
KDP cover size calculator
Spine width and full wrap dimensions for an Amazon KDP paperback. Uses the same geometry Pageling uses to generate real print files, so the numbers match what a finished cover actually measures.
Printed sides, not spreads. Must be even, minimum 24.
Your cover file
17.325 × 8.750 in
Spine 0.075 in · bleed 0.125 in on all four outer edges
- Spine width
- 0.075 in
- Full wrap width
- 17.325 in
- Full wrap height
- 8.750 in
- Front cover starts at
- 8.700 in from the left
- Spine starts at
- 8.625 in from the left
- Barcode keep-clear
- 2.00 × 1.20 in, bottom-right of back cover
No spine text. KDP requires 100+ pages before it will accept lettering on the spine, so plan for colour only.
Standard colour is deliberately not offered here. It prints on a different stock from premium colour and published figures for its per-page thickness disagree by as much as a third — enough to produce a rejected cover. Check KDP’s own calculator if you are printing standard colour.
The formula
Spine width is page count multiplied by the paper caliper. Everything else follows from it:
spine = page count × caliper width = bleed + trim width + spine + trim width + bleed height = bleed + trim height + bleed bleed = 0.125 in
KDP’s per-page calipers:
| Paper | Caliper per page |
|---|---|
| Black ink, white paper | 0.002252 in |
| Black ink, cream paper | 0.0025 in |
| Premium colour | 0.002347 in |
Spine width reference
Common page counts, in inches. Spine width does not depend on trim size — only on page count and paper.
| Pages | B&W white | B&W cream | Premium colour |
|---|---|---|---|
| 24 | 0.054 | 0.060 | 0.056 |
| 32 | 0.072 | 0.080 | 0.075 |
| 40 | 0.090 | 0.100 | 0.094 |
| 48 | 0.108 | 0.120 | 0.113 |
| 60 | 0.135 | 0.150 | 0.141 |
| 80 | 0.180 | 0.200 | 0.188 |
| 100 | 0.225 | 0.250 | 0.235 |
| 120 | 0.270 | 0.300 | 0.282 |
| 150 | 0.338 | 0.375 | 0.352 |
| 200 | 0.450 | 0.500 | 0.469 |
| 300 | 0.676 | 0.750 | 0.704 |
Frequently asked questions
- How do you calculate spine width for a KDP paperback?
- Multiply your interior page count by the paper caliper: 0.002252 in for black ink on white paper, 0.0025 in for cream, and 0.002347 in for premium colour. A 32-page premium-colour book has a spine of 32 × 0.002347 = 0.075 in.
- Does page count mean pages or spreads?
- Printed sides. One sheet of paper is two pages. If your picture book has 16 illustrated spreads, that is 32 pages. Counting spreads gives you a spine half the width it should be, which is the single most common cover mistake.
- Why does my cover need to be one file instead of three?
- KDP prints the paperback cover as a single flat sheet wrapping back cover, spine and front cover, with bleed on all four outer edges. Uploading only a front cover image will not work for a paperback.
- Can I put the title on the spine?
- Only at 100 pages or more. Below that KDP will not accept spine text because the spine is too narrow to print reliably without drifting onto the front or back cover. Most picture books therefore have colour-only spines.
- What is the barcode area I need to leave clear?
- A 2 × 1.2 in box at the bottom-right of the back cover. Artwork may sit underneath it, but keep text and logos out of it — Amazon prints over that area.