How KDP works out your cover size
A KDP paperback cover is one flat image: the back cover, the spine and the front cover side by side, with an extra strip of bleed around the outside that's trimmed off after printing. Get any part of the maths wrong and KDP rejects the file, or the spine wraps onto the front.
Width = bleed + back cover + spine + front cover + bleed
Height = bleed + trim height + bleed
Bleed is 0.125 in (3.2 mm) on the top, bottom and outside edges. The front and back are each your trim width. The spine is the only part that changes from book to book, because it depends on your page count and paper.
Worked example
A 6 × 9 in paperback with 320 pages on cream paper:
- Spine: 320 × 0.0025 in = 0.800 in
- Width: 0.125 + 6 + 0.800 + 6 + 0.125 = 13.050 in
- Height: 0.125 + 9 + 0.125 = 9.250 in
- At 300 dpi, that's a canvas of 3,915 × 2,775 pixels
Spine width per page
| Interior and paper | Per page | Page range |
|---|---|---|
| Black & white, white paper | 0.002252 in | 24 to 828 |
| Black & white, cream paper | 0.0025 in | 24 to 776 |
| Standard colour, white paper | 0.002252 in | 72 to 600 |
| Premium colour, white paper | 0.002347 in | 24 to 828 |
Maximum page counts are lower on some larger trims (for example 590 pages on white paper at 8.5 × 11 in), and standard colour isn't offered at A4. The calculator checks your combination for you.
Spine widths at a glance
| Pages | White | Cream | Standard colour | Premium colour |
|---|---|---|---|---|
| 100 | 0.225 in | 0.250 in | 0.225 in | 0.235 in |
| 200 | 0.450 in | 0.500 in | 0.450 in | 0.469 in |
| 300 | 0.676 in | 0.750 in | 0.676 in | 0.704 in |
| 400 | 0.901 in | 1.000 in | 0.901 in | 0.939 in |
| 500 | 1.126 in | 1.250 in | 1.126 in | 1.173 in |
The spine doesn't depend on trim size, only on pages and paper, so the same table works for every trim.
Full cover size by trim (200 pages, white paper)
| Trim size | Full cover with bleed | Canvas at 300 dpi |
|---|---|---|
| 5 × 8 in | 10.700 × 8.250 in | 3,210 × 2,475 px |
| 5.5 × 8.5 in | 11.700 × 8.750 in | 3,510 × 2,625 px |
| 6 × 9 in | 12.700 × 9.250 in | 3,810 × 2,775 px |
| 6.14 × 9.21 in | 12.980 × 9.460 in | 3,894 × 2,838 px |
| 7 × 10 in | 14.700 × 10.250 in | 4,410 × 3,075 px |
| 8 × 10 in | 16.700 × 10.250 in | 5,010 × 3,075 px |
| 8.5 × 11 in | 17.700 × 11.250 in | 5,310 × 3,375 px |
The rules your cover has to follow
Text on the spine
KDP only allows spine text on books of 80 pages or more. Keep it at least 0.0625 in (1.6 mm) inside each spine edge, because the fold can shift slightly in printing.
Front and back cover text
Keep all text at least 0.125 in (3.2 mm) inside the trim line, and no smaller than 7 point. Anything closer to the edge risks being cut off.
Barcode
If you don't add your own, KDP prints the barcode in a 2 × 1.2 in white box at the bottom right of the back cover, beside the spine. KDP's guidance is to keep it at least 0.25 in from the spine and the trim edges. Keep that area clear or the barcode will cover your design.
The file itself
- One PDF with back cover, spine and front cover as a single image
- At least 300 dpi, with images at 100% size and flattened to one layer
- Under 650 MB (KDP recommends 40 MB or less)
- The template guide layer hidden before you export
Using the template
- Enter the trim size, interior and paper, and your final page count. Check the page count first: if it changes later, your spine width changes too.
- Download the PNG to use as a guide layer in Canva, Affinity, Photoshop or GIMP, or the PDF for programs that prefer it.
- Design on top. Keep text inside the blue dashed lines, let background art run to the outer edge so the bleed is filled, and leave the grey barcode box clear.
- Hide the template layer and export a PDF at the full cover size shown above.
Questions
Does this work for hardcovers?
No. KDP hardcovers have different bleed, wrap and hinge measurements. This tool is for paperbacks only.
Why is my spine different to someone else's with the same page count?
Paper. Cream paper is thicker than white, so a cream book has a wider spine than a white book with the same number of pages.
Does KDP have its own calculator?
Yes, and it's worth checking your final numbers against it before you order a proof. This tool gives you the same figures instantly, with a preview and a template you can download without leaving the page.
Figures from KDP's help pages, checked 28 October 2026.