Free KDP cover calculator
Enter your trim, paper and page count to get the spine width and the full wraparound cover size, in inches and millimetres. No sign-up, no watermark. The same maths behind our Publisher Studio.
Your cover
Recalculates as you change the trim, paper or page count.
- Spine
- 0.270 in6.9 mm
- Cover width
- 12.520 in318.0 mm
- Cover height
- 9.250 in234.9 mm
6" x 9" (Trade Digest), 120 pages, with bleed. This book has enough pages for a printed spine title.
How to size a KDP cover
- 1Pick your trim and paper. Choose the finished page size and whether the interior prints on white, cream or in colour. The paper sets how thick each page is.
- 2Enter the page count. Type the number of pages in the interior, from 24 to 828. The spine grows with the count, so use the real final number.
- 3Read the spine and cover size. You get the spine width and the full wraparound cover width and height, with bleed, in inches and millimetres, ready to size your cover artwork to.
Making the book too?
Publisher Studio compiles journals, planners and puzzle books, works out the spine from the final page count, sizes the cover to it and exports a print-ready 300 DPIinterior and a wraparound cover at any standard trim, to KDP, Gelato or Kindle.
See the journal makerQuestions
- How is the spine width worked out?
- The spine width is the page count times the paper thickness per page: about 0.002252 inch for white, 0.0025 inch for cream and 0.002347 inch for colour on KDP. So a 120-page white-paper book has a spine near 0.27 inch.
- What is the full cover size?
- The full cover is one flat image holding the back panel, the spine and the front panel, plus 0.125 inch of bleed on every outside edge. The width is two trim widths plus the spine plus the bleed; the height is the trim height plus bleed top and bottom.
- Can I put a title on the spine?
- KDP prints a spine title only from 79 pages up, because a thinner spine cannot hold legible text. The calculator tells you whether your page count clears that.
- Is the calculator exact?
- It uses KDP published paper thicknesses and the standard bleed, so it matches KDP for a paperback. Specs can change, so confirm on KDP before you upload, and note that hardcover and other services size covers differently.
- Does Publisher Studio do this for me?
- Yes. When you build a journal, planner or puzzle book, Publisher Studio works out the spine from the final page count, sizes the cover to it and gates the export, so you do not calculate it by hand. This tool is for sizing a cover before you build the book.