Everything else can be trimmed; the spine is printed before the book exists.
2026-10-074 minPress Bench
A number you cannot fix later
A cover is printed flat, folded and bound around a text block that has not yet been made. If the spine is wrong, the cover is wrong. Trimming can rescue a margin; nothing rescues a spine that is too narrow for the text.
Build it from stock
Measure a printed leaf with a micrometer. Multiply by the leaf count, add two cover thicknesses and the bindery allowance. Then round to a size the bindery can hold. A mill datasheet is a starting point, not a measurement.
The check to keep
Ask for a bound dummy on the actual stock before the cover run. Measure the dummy spine, compare it with the calculated figure, and write the difference on the ticket. That difference is the reprint you avoided.
