Case-making calculator
Print shops publish calculators for their own presses; the hand binder works from forum posts. This takes the three numbers on your bench — trim size, text-block thickness, board — and returns the whole cut list: two boards, the spine piece, the hinge gaps, the flat case, the cloth cut, the mull width. The hinge is 1.5 × board thickness, the convention every binding manual carries; the rest is stated arithmetic from your inputs.
Caliper the pressed block. The spine calculator gives it from pages + paper.
How far the case overhangs the block. 3 mm is customary; 2 mm for small books.
- Boards (cut 2)
- 151 × 216 mmheight gains two squares; width only the fore-edge square
- Spine piece
- 17.5 × 216 mmblock thickness plus the covering's wrap over each board edge
- Hinge gaps
- 3.8 mm each1.5 × board, both sides of the spine
- Flat case, as laid out
- 327 × 216 mmboards + hinges + spine, before covering
- Cloth / paper cut
- 362 × 251 mmcase + 17.5 mm turn-in on every edge
- Mull width
- 55 mmspine + 20 mm onto each board, after backing
Arithmetic on this machine, nothing to upload. Grain rule the calculator cannot check: board and cloth grain run the case's HEIGHT.
Where each number comes from
Boards: trim plus squares
Height gains a square top and bottom; width gains one on the fore edge only — the spine edge of the board meets the hinge, not an overhang. 3 mm squares are customary; 2 mm suits small trims.
Spine piece: block plus board
Width is your calipered block thickness plus one board thickness — the covering wraps over each board edge it meets. Height matches the boards.
Hinge: one and a half boards
The gap between board and spine piece is 1.5 × board thickness, per side. Too narrow and the cover fights the joint; too wide and the boards sag off the book. It is the one number in the list that is convention rather than arithmetic, and it is the convention because it works.
The order of operations
A case goes together flat, then goes on the book:
- Glue the case flatBoards and spine piece laid to the calculator's flat-case dimensions on the cloth cut, hinges open, everything squared. Press under weight.
- Turn in the edgesThe turn-in allowance is board + 15 mm — already in the cloth cut. Mitre the corners at 45° so the bulk lands diagonally, not stacked.
- Case inCased onto the block with mull spanning the spine and 20 mm onto each board — that width is in the list too. Press overnight; the hinge does the rest.
Questions people actually ask
Why 1.5 × board for the hinge?
It is the published convention across binding manuals: enough gap for the covering to fold and the joint to open, without a ridge of empty board. At 2.5 mm board that is 3.75 mm per side — the calculator shows it so you can mark it, not guess it.
My spine is rounded and backed — same numbers?
Caliper the rounded block at its thickest and the spine piece width still holds; the rounding spreads across the width. Backing swells the shoulders slightly — add a millimetre to the spine piece if your shoulders are pronounced.
Can I use this for a Bradel binding?
Yes — Bradel cases are built to the same board-spine-hinge arithmetic; the method differs (spine piece set to a false shoulder), the dimensions do not.
What board should I buy?
2.5 mm greyboard (chipboard) is the workshop standard. 2.0 mm for small or floppy books, 3.0 mm for large commemorative ones. The calculator's hinge follows whichever you pick.
How much cloth do I need for several books?
The cloth cut is one book's covering — the yardage calculator turns it into roll metres per book and books per roll.
The Heirloom edition is this arithmetic done by hand, in Durban.
See the hand-bound editionThis is one of the tools — or see everything we’ve written.