Observed arrival · 2026-09-30

Paperback Math’s print-book calculators

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Editorial interest 78/100 Selection signal · not a rating of the site

A free set of calculators and checkers for print-on-demand book covers, interiors, trim sizes, royalties, and print costs.

Landing page captured for the 2026-09-30 issue.

For: Self-published authors preparing print-on-demand books
Worth noticing: The IngramSpark paperback tool says its spine widths are measured using IngramSpark’s own calculator rather than estimated.

Field notes

The page organizes tools by Amazon KDP, Lulu, and IngramSpark, with trim-size menus listing 17 KDP paperback sizes, five KDP hardcover sizes, and 15 sizes each for Lulu and IngramSpark. Cover checkers are described as checking dimensions, DPI, and safe zones; downloadable templates are listed at 300 DPI. The IngramSpark paperback tool says its spine measurement comes from IngramSpark’s calculator.

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○OpenPublic substance visible

✦PrettyNotable craft visible

●ProPolished or operationally mature

◎NicheUnusually specific use

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