KDP Cover Size & Spine Width Calculator

A paperback cover is one flat image that wraps around the book: back cover on the left, spine in the middle, front cover on the right. KDP prints it on a larger sheet and trims it down, so the file has to be bigger than the finished book in three ways.

• Bleed. Add 0.125 in (3.2 mm) to the top, bottom and both outside edges. Anything in that strip is cut off. It exists so a small shift in the cutter leaves color, not a white sliver, at the edge. Extend your background all the way into it.
• Spine. The spine is as wide as the pages are thick. KDP gives a per-page figure for each paper, and the calculator multiplies it by your page count.
• Two trim widths. The back and front each match the trim width of the interior, so a 6 × 9 book has two 6 in panels.

Put together: full width = 0.125 + trim width + spine + trim width + 0.125, and full height = trim height + 0.25. At the 300 DPI KDP recommends for print, multiply both by 300 to get the pixel size to set up in your design app.

KDP publishes these per-page thicknesses for paperbacks:

• Black ink, white paper: 0.002252 in (0.0572 mm) per page. Usual for non-fiction, workbooks and anything with images.
• Black ink, cream paper: 0.0025 in (0.0635 mm). Cream is a little thicker, so the same novel has a wider spine on cream than on white: 0.75 in against 0.676 in at 300 pages.
• Standard color, white paper: 0.002252 in, the same as white. Standard color needs at least 72 pages and allows up to 600.
• Premium color, white paper: 0.002347 in (0.0596 mm). Picture books and photo-heavy books usually print on premium color.

Use the final page count of the interior PDF you upload, including front matter and blank pages, not the count from your word processor. If the interior changes by even a few pages, the spine changes with it, and a cover built for the old count can be rejected or print with the spine text slipping onto a fold. If you don’t have an interior yet, estimate it with our book page count calculator, then recalculate the cover once the interior is final.

Spine text is only allowed on books with more than 79 pages. Thinner books get a plain spine, which is why a 32-page picture book shows only color on the shelf.

The downloadable SVG is drawn at full size, one unit per inch, so it drops into Affinity, Illustrator, Inkscape, Photoshop or Canva at the right scale. Put it on its own layer above or below your artwork and hide it before you export the PDF. It shows:

• Bleed in pink and the trim line in red.
• Spine folds in blue. KDP allows up to 0.0625 in (1.6 mm) of variance either side of each fold, so keep spine text that far inside.
• Safe areas as green dashes. KDP’s minimum is 0.125 in from the trim; the template uses 0.25 in, which leaves room for the cutter and reads better on the shelf. Keep titles, author names and back-cover copy inside it.
• The barcode box, 2 × 1.2 in at the lower right of the back cover. If you don’t supply your own barcode, KDP prints one there on a white box, covering whatever artwork sits underneath.

Export the finished cover as a single PDF at the full size the calculator shows, with images at 300 DPI. Then check it in KDP’s previewer, which overlays its own guides and flags anything in the wrong place.

The usual reasons a cover gets sent back are a file built for the wrong page count, so the size doesn’t match; text inside the bleed or too close to a fold; spine text on a book under 80 pages; and artwork that stops at the trim line, leaving no bleed. Running the numbers again after the interior is final catches the first, and the template’s guides catch the rest.

KDP case laminate hardcovers are built differently. The cover image has to extend 0.51 in (15 mm) past each edge so it can wrap around the board and glue to the inside. There is a 0.4 in (10 mm) hinge between the spine and the front and back panels where text gets distorted. Hardcovers come in five trims and need 75 to 550 pages, and the spine includes a board allowance KDP doesn’t publish as a formula. Use KDP’s cover calculator for those instead of guessing.

IngramSpark uses its own paper and spine figures, so a KDP cover won’t fit an IngramSpark book of the same page count exactly. Its cover template generator builds the right file and includes the barcode for your ISBN.

Numbers checked on November 9, 2026 against KDP’s help pages: create a paperback cover, trim size, bleed and margins and create a hardcover cover. Page limits differ by trim: 8.5 × 11 and 8.5 × 8.5 stop at 590 pages on white paper, for example, and the calculator applies the limit for the trim you pick.

Once you know the size, the cover still has to work as a thumbnail and on the shelf. The lesson on book covers that sell covers genre conventions and type. Anthra’s cover studio uses the same geometry as this calculator: design the front, back and spine together and export a print-ready wrap PDF from the AI book generator. While you’re pricing the book, the KDP royalty calculator shows what each paperback earns at the page count you entered here, and the book blurb generator drafts the back-cover copy.