Book cover size calculator
Enter your trim size, page count and paper stock. Everything updates as you type, and the URL updates with it so you can save or share the exact result.
Full cover canvas
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Spine width
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Spine (mm)
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Pixels
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Spine text
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How it is worked out
| Step | Calculation | Result |
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Common questions
Is this calculator free?
Yes, with no sign-up and no limit. It runs in your browser — nothing is sent anywhere.
Which printer are these numbers for?
Amazon KDP paperbacks. The geometry is the same for any perfect-bound book, but the per-page paper thickness and bleed are KDP’s published figures.
Why is my result different from another calculator?
Most likely the other one adds a 0.06″ constant to the spine. That is not in the printer’s specification. This calculator uses page count × paper thickness with nothing added.
Can I link to a specific result?
Yes. The URL updates as you change the inputs, so you can copy it or bookmark it and it will reopen with the same numbers.