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Bag Cutting Dimensions with Fixed One-Inch Allowances

Relate finished bag height, width and depth to the captured rectangular cutting pattern, with fixed one-inch allowances and an optional boxed-corner measure.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

For a bag 30 cm high, 20 cm wide and 10 cm deep, this pattern calls for fabric 62.54 cm wide by 37.54 cm high. The optional boxed-corner measure is 5 cm.

Pattern width = 2w + 2d + 1 in; pattern height = h + d/2 + 1 in; boxed-corner measure = d/2

Worked example

Enter these known values and leave the other values blank.

Optional boxed-corner measure
Show boxed-corner measure
Finished bag height h
30 cm
Finished bag width w
20 cm
Finished bag depth d
10 cm
Pattern width
62.5 cm
Pattern height
37.5 cm
Boxed-corner measure
5 cm

Assumptions and limitations

  • This is one fixed cutting pattern, not a universal bag design. It adds a total one inch to pattern width and a total one inch to pattern height. Each fixed allowance is exactly 2.54 cm even when dimensions are entered in centimeters.
  • The pattern dimensions include finished width/depth relationships and the fixed allowances in the displayed formulas. Fabric quantities for lining, handles, closures, pockets, shrinkage, pattern matching and scraps are not added.
  • The optional choice controls whether the boxed-corner measure d/2 is displayed. Hiding it does not set depth to zero or change the pattern-width/height equations. The source choice starts locked, but you can still change its selected option.
  • Finished dimensions and pattern dimensions are positive. To work backward, enter compatible pattern and finished dimensions while leaving the desired unknown empty; too little material can imply a rejected nonpositive finished dimension.

Common questions

Does entering centimeters change the allowance to one centimeter?

No. Both literal allowances remain one inch, exactly 2.54 cm. Only the representation of the dimensions changes with the unit controls.

What happens when I hide the boxed-corner measure?

Only that measure disappears. Depth continues to affect the pattern width and height; it is not automatically set to zero.

Does the result include lining and handles?

No. The model provides the rectangular pattern dimensions in its fixed formulas. Add lining, handles, hardware, matching and other project-specific material requirements separately.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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