Use the setup that matches your final book
Choose the binding, trim, paper, and interior you intend to publish. Use the final formatted page count when available. An odd count rounds up to the next even count, which then drives the margin band, spine, and page-range check.
Select interior bleed according to the interior design, not whether the cover extends to its edge. Choose units for the layout software you use and DPI for pixel targets. Pixel dimensions are conversion targets, not evidence that an exported PDF has the right resolution or size.
An unsupported combination prevents calculation. A supported combination outside its page range can still produce dimensions with a warning; those numbers do not make the book eligible. Reading direction changes the cover segment order, not its dimensions, and does not verify language eligibility.
Editing the setup clears the previous calculation. After revising the book, calculate again before copying its receipt. Setup values are calculated in your browser; this tool reads no manuscript or PDF.
Page count changes more than the spine
A thicker book needs a wider inside margin at the relevant page-count boundary. This calculator applies the minimum margin band to the effective even page count, so an odd count near a boundary can change more than the final number of pages. Minimum margins are production constraints, not a complete typography or readability recommendation. See KDP's submission guidelines.
Paper and ink also change spine width. The calculation uses the selected profile's coefficient from KDP's paperback cover requirements, including the published groundwood coefficient. Do not carry a spine measurement from one paper or color choice into another setup.
Interior bleed does not switch cover bleed off
Interior bleed adds 0.125 inch to the page width and 0.25 inch to its height. Without interior bleed, the page matches the trim size. The paperback cover has its own required outer bleed regardless of that interior setting.
The calculations start from inch-based dimensions, then convert to millimeters and rounded pixel targets. Changing the display unit does not select a different paper rule or create a new print specification.
Confirm hardcover geometry with KDP's template
The hardcover estimate uses the documented 0.51-inch wrap and 0.4-inch hinge allowances. The reviewed hardcover cover guidance does not supply the single closed total-width formula used by this local planning model. Treat its spine and full cover size as estimates, not an official template.
Use KDP's cover calculator with the final book settings before preparing the cover file. This tool's dated source table cannot inspect the exported PDF, check the design, or establish KDP acceptance.