THE NUMBERS, EXPLAINED
How to use this calculator.
Flat layout of two equal boards and one spine strip with two joints. Cloth turn-ins surround the entire assembly; grain and decorative pattern allowance are external.
Start with your inputs
Enter cover board width (mm), cover board height (mm), spine strip width (mm), joint gap on each side of spine (mm), cloth turn-in on each outside edge (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Cover board width (mm) | 140 |
| Cover board height (mm) | 200 |
| Spine strip width (mm) | 20 |
| Joint gap on each side of spine (mm) | 6 |
| Cloth turn-in on each outside edge (mm) | 15 |
A worked example
With the example inputs above, case assembly width before turn-ins (mm) is 312. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Case assembly width before turn-ins (mm) | 312 |
| Cloth cut width (mm) | 342 |
| Cloth cut height (mm) | 230 |
| Cloth blank area (square mm) | 78,660 |
How this is calculated
Case assembly width before turn-ins (mm)
Add two boards, spine and two joints.
Cloth cut width (mm)
Add left and right turn-ins.
Cloth cut height (mm)
Add top and bottom turn-ins.
Cloth blank area (square mm)
Multiply cloth cut dimensions.
Symbols and units
- a
- Cover board width (mm)
- b
- Cover board height (mm)
- c
- Spine strip width (mm)
- d
- Joint gap on each side of spine (mm)
- e
- Cloth turn-in on each outside edge (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Flat layout of two equal boards and one spine strip with two joints. Cloth turn-ins surround the entire assembly; grain and decorative pattern allowance are external.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Case assembly width before turn-ins (mm); Cloth cut width (mm); Cloth cut height (mm); Cloth blank area (square mm). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Flat layout of two equal boards and one spine strip with two joints. Cloth turn-ins surround the entire assembly; grain and decorative pattern allowance are external.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax Prealgebra 2e — arithmetic and proportions ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
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