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Book Spine Calculator for KDP Covers

Enter the trim size, page count and paper stock to calculate the spine width and full flat cover dimensions.

Free · No sign-up · Nothing uploaded

The usual choice for non-fiction and most genre fiction.

Spine width

0.676″

300 pages × 0.002252″ per page

Full cover widthBack + spine + front, including bleed
12.926″
Full cover heightTrim height plus bleed top and bottom
9.250″
On cream paperThe same book, the other stock
0.750″+0.074″

Don't know your page count yet? The margin calculator estimates it from a word count — or format the interior and it will tell you exactly.

The input people forget

The paper changes the spine

Spine width is page count multiplied by the thickness of one sheet, so the stock you choose at upload changes the physical object. The same 300-page book, on each of KDP's papers:

  • Black & white on white paper0.676″

    The usual choice for non-fiction and most genre fiction.

  • Black & white on cream paper0.750″

    Common for literary fiction. Thicker than white, so the spine grows.

  • Premium colour on white paper0.704″

    Only if the interior is actually in colour.

Before you design the cover

Under 80 pages? Leave the spine text off

KDP will not print text on a spine narrower than that, because the binding cannot hold it straight enough to be readable. A cover submitted with spine text below the threshold comes back rejected, and it is the sort of thing discovered late.

Use KDP's cover template for production

These numbers tell you the size of the object. KDP generates a template PNG or PDF for your exact trim, page count and paper, with the bleed and barcode zones marked — design on that, not on a rectangle of these dimensions.

This calculator is for planning and for checking a quote. It does not replace their template or their final file checker.

Next

Don't know the final page count yet?

The spine depends on it, and a page count is only real once the interior is set — margins, trim and type size all move it. Format the interior first and the number it reports is the one to bring back here.

Calculated the spine?

Create the exact print interior first

Questions

Spine width, answered

How is spine width calculated?

Page count multiplied by the thickness of one sheet, which depends on the paper. KDP publishes a figure per stock: 0.002252 inches per page for black and white on white, 0.0025 on cream, 0.002347 for premium colour. There is no rounding and no minimum — a 120-page book on white has a spine of 0.27 inches.

Why does cream paper make a thicker book?

Because it is physically thicker paper. The same 300-page manuscript is 0.676 inches on white and 0.750 on cream — nearly a tenth of an inch wider. That is enough to matter on a cover, which is why the calculator shows you both.

Why can't I put text on my spine?

KDP will not print spine text below 79 pages. There is not enough width to place type without risking it creeping around onto the front or back, so thin books get a blank spine. Worth knowing before you design a cover around a spine title.

What is bleed, and why is the cover bigger than the book?

Bleed is the extra margin that gets trimmed off, so that anything meant to run to the edge actually does rather than leaving a white sliver. A cover is one flat sheet — back, spine, front — with 0.125 inches of bleed around the outside. There is no bleed between the panels, because they are not separate pieces.

Do I need this if KDP has a cover template?

KDP's template generator gives you the same geometry as a downloadable file, and you should use it when you actually build the cover. This is for the moment before that — checking whether a spine is wide enough for a title, or how much a paper choice will change the design, without going through a form for each variation.

Checked against the source

The requirements on this page are published by the organisations below, not by us. We last read them in September 2026 and compared them against what the tool produces. If a requirement has changed since, the source is right and we are wrong — tell us and we will fix it.