Inputs
Result
- Spine width
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- Full cover size
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- Full cover (pixels, 300 DPI)
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- Front / back (trim)
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Spine width = page count × paper factor (white 0.002252, cream 0.0025, premium color 0.002347 in/page); full cover adds 0.125 in bleed on every side. Reference values from KDP — minimum 24 pages, and they can change, so confirm with the official cover template. Factual calculation only.
Calculate the **cover sizes** you need to self-publish on Amazon KDP (Kindle Direct Publishing). In **paperback** mode, pick the trim size, enter the **page count**, and choose the paper type (white, cream, standard color, or premium color) to get the **spine width** and the **full-cover** dimensions — back cover + spine + front cover + 0.125 in bleed on every side. Switch the display between inches and millimetres, and read the **300 DPI pixel** dimensions you need to upload, with a diagram showing how the back, spine and front are laid out. In **ebook (Kindle)** mode, the calculator works from the recommended 2,560 × 1,600 px cover (1.6:1, height:width) and checks that the shortest side is at least 1,000 px and the longest no more than 10,000 px. The spine uses KDP's published paper factors (white 0.002252, cream 0.0025, premium color 0.002347 in/page) — this is **factual calculation only**, and because figures can change, confirm the final numbers with the official KDP cover template. Your inputs are never sent anywhere; everything runs in your browser with no sign-up.
How to use
- Choose 'Paperback', pick the trim size (e.g. 6 × 9 in), enter the book's page count and select the paper type. Pick 'Custom…' to type the width and height directly.
- The spine width and the full-cover size (back + spine + front + bleed) appear in inches/mm and as 300 DPI pixels. Toggle the unit between inch and mm.
- Switch to 'Ebook (Kindle)' to compute the width at the recommended 1.6:1 ratio from a cover height in pixels, and check it stays within KDP's range (shortest side ≥ 1,000 px, longest ≤ 10,000 px).
FAQ
How is the KDP spine width calculated?
Spine width = page count × a paper factor. This tool uses KDP's published factors (white 0.002252, cream 0.0025, premium color 0.002347 inches per page). Paperbacks start at a minimum of 24 pages, and the spine grows wider as the page count increases.
What does the full cover size include?
The full cover (the single wraparound image you upload) is back cover + spine + front cover plus 0.125 in bleed on the left and right, and the height is the trim height plus 0.125 in bleed top and bottom. The 300 DPI pixel dimensions are shown alongside.
What is the recommended ebook (Kindle) cover size?
KDP recommends an ebook cover of 2,560 × 1,600 px (1.6:1, height:width). Keep the shortest side at least 1,000 px and the longest no more than 10,000 px. Enter a height and the tool gives the 1.6:1 width and flags whether it is in range.
Does it support trim sizes like 6 × 9 in?
Yes. Common KDP trim sizes from 5 × 8 up to 8.5 × 11 in are preset, with A5 and A4 equivalents noted. For any size not listed, pick 'Custom…' and type the width and height in inches.
Are my inputs uploaded?
No. Trim size and page count are never sent anywhere — everything runs in your browser, free and with no sign-up. These are reference figures using factual calculation only; always confirm the final numbers with the official KDP cover template.