Free tool
KDP Cover Size Calculator
Spine width and the full-wrap cover canvas for your paperback — computed from KDP’s own published formula, shown in inches and millimetres. Dimensions are never rounded down: a canvas even slightly too small is an upload rejection.
Enter your final page count — and, for a custom format, both trim fields — to get the exact cover dimensions.
KDP doesn’t accept that page count for this paper: the allowed range is–––pages. Pick another ink/paper combination or adjust the interior.
That trim size is outside KDP’s limits — width must stay within 4–8.5″ and height within 6–11.69″.
Full cover file (with bleed)
–″ ×–″
= – × – mm · width × height
Spine width: –″(– mm)
Under 80 pages: KDP prints spine text only on books with more than 79 pages — leave your spine as background color only.
Largest-format caution: at this size KDP’s page limits become trim-dependent. The rows Amazon has published (the A4-class 8.27″-wide trims) cap at 780 pages on white/premium color and 730 on cream, standard color isn’t offered at 8.27″ × 11.69″ — and for the other large trims no rows are published at all. The geometry above is exact either way — but confirm this exact combination in the KDP setup wizard before you design.
From KDP’s published cover formula — the same math its template generator uses. Keep spine text 0.0625″ away from the spine edges.
How the math works
KDP’s cover guidelines define the full-wrap canvas as: 0.125″ bleed + back cover + spine + front cover + 0.125″ bleed across, and 0.125″ bleed + trim height + 0.125″ bleed down. The spine is page count × the paper’s per-page thickness: white paper 0.002252″ per page, cream 0.0025″, premium color 0.002347″, standard color 0.002252″. That’s the whole formula — the value of a calculator is not doing it by hand at 11 pm, and never rounding a dimension down.
Page counts KDP accepts depend on the combination: black ink takes 24–828 pages on white paper and 24–776 on cream; standard color takes 72–600; premium color 24–828. The calculator refuses page counts outside those ranges outright — and on the largest trims, where the published limits turn trim-dependent (KDP’s A4-class rows cap at 780/730, and rows for the other large trims aren’t published), it shows a caution next to the result instead of quietly promising the wizard will say yes.
FAQ
What size should my KDP cover file be?
The full-wrap cover PDF is: 0.125" bleed + back cover + spine + front cover + 0.125" bleed wide, and 0.125" bleed + trim height + 0.125" bleed tall. For a 6" x 9" book with 300 white pages that comes to 12.926" x 9.25". This calculator does that arithmetic from KDP’s published formula.
How is the spine width calculated?
Page count times the paper’s per-page thickness, from KDP’s cover guidelines: white paper 0.002252" per page, cream 0.0025", premium color 0.002347", standard color 0.002252". A 333-page white-paper book gets a 0.75" spine.
Why can’t I put text on the spine of my book?
KDP prints spine text only on books with more than 79 pages, and requires 0.0625" of clearance between the text and the spine edges. Below 80 pages the spine is simply too thin — plan a spine with background color only.
Does this calculator work for hardcovers or groundwood paper?
No, and honestly so. Hardcover cases use a different construction (wrap, board and hinge allowances) that KDP handles via its own template generator, and Amazon has not published a spine multiplier for the newer groundwood paper. For both, download the template from KDP’s cover-templates page instead of trusting any third-party number — including ours.
What page counts does KDP accept?
The overall ranges: black ink on white paper 24–828 pages, on cream 24–776; standard color 72–600; premium color 24–828. Custom trim sizes must stay within 4–8.5" wide and 6–11.69" tall. One catch on the largest formats: the limits become trim-dependent there. The rows KDP has published — the A4-class 8.27"-wide trims, in its kdp.amazon.co.jp table — cap at 780 pages on white or premium color paper and 730 on cream, standard color isn’t offered at 8.27" x 11.69", and Amazon publishes no equivalent rows for the other large trims. Above those documented caps the calculator shows a caution: confirm the exact combination in the KDP setup wizard.
The cover is the easy math. The niche is the hard one.
This page is formula arithmetic; whether the book inside the cover will sell is a data question. KDPie scans a niche with real Amazon data — demand, competitors, rank history — and gives you a clear verdict before you invest in the design.
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