A paperback cover on KDP is one image: back cover, spine and front cover side by side, with a margin of bleed all round. Its exact size depends on three things — the trim size, the page count and the paper — and getting it wrong is one of the most common reasons KDP rejects a cover file.
The formula
0.125 + trim width + spine + trim width + 0.125 in
trim height + 0.25 in
The 0.125 in bleed runs round every outside edge, so the height gains 0.125 in at the top and 0.125 in at the bottom.
page count × paper thickness per page
Spine width by paper
| Paper and ink | Per page | 200 pages |
|---|---|---|
| White, black ink | 0.002252 in | 0.450 in |
| Cream, black ink | 0.0025 in | 0.500 in |
| White, standard colour | 0.002252 in | 0.450 in |
| White, premium colour | 0.002347 in | 0.469 in |
KDP only allows text on the spine of books with more than 79 pages; below that the spine is too thin to print on reliably. Keep spine text well inside the spine, because the fold can drift slightly from copy to copy.
A worked example
A 6 × 9 in novel with 300 pages on cream paper: the spine is 300 × 0.0025 = 0.75 in. The cover is 0.125 + 6 + 0.75 + 6 + 0.125 = 13.0 in wide and 9 + 0.25 = 9.25 in tall — 3,900 × 2,775 pixels at 300 DPI.
Preparing the file
- Resolution: 300 DPI at full size, so a 13 in wide cover is 3,900 pixels wide.
- Format: a single PDF of the whole wrap: back on the left, front on the right.
- Safe zone: keep text and faces well away from the trim line, because the bleed is cut off.
- Barcode: KDP places it on the back cover; leave the lower right of the back cover clear.
- Template: KDP’s cover calculator on its website generates a downloadable template for your exact trim size and page count. Use it to check your layout before you upload.
Why the cover matters for ads
Your cover is what an ad shows: a thumbnail a few centimetres tall next to a dozen competitors. The cover does most of the work of getting the click, and every click you pay for is wasted if the thumbnail does not say what the book is at a glance. Check your cover at thumbnail size before you spend anything on ads. How to advertise your book.
Common questions
How do I calculate my KDP cover size?
Width = 0.125 in bleed + trim width + spine width + trim width + 0.125 in bleed. Height = trim height + 0.25 in. Spine width = page count × the paper’s thickness per page (0.002252 in for white, 0.0025 in for cream).
How wide is the spine of a KDP paperback?
Page count multiplied by the paper thickness: 0.002252 in per page for white paper, 0.0025 in for cream, and 0.002347 in for premium colour. A 200-page book on white paper has a 0.45 in spine.
What size is a 6 × 9 KDP cover?
It depends on the page count. For 200 pages on white paper the spine is 0.45 in, so the full cover is 12.70 × 9.25 in. For 300 pages on cream it is 13.0 × 9.25 in.
Can I put text on the spine?
Only if the book has more than 79 pages. Thinner books have no spine text.
What resolution should a KDP cover be?
300 DPI at the full printed size. A 12.7 in wide cover needs to be about 3,810 pixels wide.
- Cover width = 0.125 + trim width + spine + trim width + 0.125 in; height = trim height + 0.25 in.
- Spine = pages × 0.002252 in (white) or 0.0025 in (cream).
- No spine text at 79 pages or fewer.
- Export at 300 DPI as one PDF: back, spine, front.
- Your cover is your ad: check it at thumbnail size before you pay for clicks.