KDP cover calculator
Spine width and the full flat cover for a KDP paperback, in inches, millimetres and pixels at 300 DPI. Bleed included, because the trim cuts into it.
0.450"
11.43 mm · 135 px at 300 DPI
12.700"
322.58 mm · 3810 px at 300 DPI
9.250"
234.95 mm · 2775 px at 300 DPI
Bleed is already included: the cover is 0.125" wider on each outside edge and taller top and bottom, because the trim cuts into it.
At 200 pages Amazon will print spine text, with 0.325" usable once the required 0.0625" clearance comes off each fold.
How the spine is worked out
One multiplication, and the only thing that varies is how thick a sheet of the chosen paper is.
| Paper | Per page | 300 pages |
|---|---|---|
| Black & white, white paper | 0.002252" (0.0572 mm) | 0.676" |
| Black & white, cream paper | 0.0025" (0.0635 mm) | 0.750" |
| Premium colour | 0.002347" (0.0596 mm) | 0.704" |
| Standard colour | 0.002252" (0.0572 mm) | 0.676" |
Standard colour and white black-and-white share a thickness — that is Amazon's own number, not a slip. Read from Amazon's paperback cover specification on 2026-08-30.
Questions
- How do you calculate KDP spine width?
- Multiply the page count by the paper's thickness: 0.002252 inches per page for black-and-white on white paper, 0.0025 for cream, 0.002347 for premium colour, and 0.002252 for standard colour. A 300-page book on white paper has a 0.676 inch spine.
- What size should a KDP paperback cover be?
- The full cover is one flat sheet: bleed + back cover + spine + front cover + bleed across, and bleed + trim height + bleed down. Bleed is 0.125 inches on every outside edge. A 300-page 6x9 book on white paper needs a 12.926 x 9.25 inch cover.
- Why is there no text on my spine?
- Amazon only prints spine text on books with more than 79 pages. Below that the spine is left blank no matter what the artwork contains, which catches out a lot of first covers.
- Does the spine change the cover height?
- No. The spine only widens the cover. Height is the trim height plus bleed top and bottom, and stays the same whether the book is 50 pages or 800.
- What resolution does a KDP cover need?
- 300 DPI. This calculator prints the pixel dimensions at 300 DPI beside the inches and millimetres, so the canvas can be set up directly.