Free · Everyday planning calculators

Circle Skirt Cutting Radius Calculator

Calculate the waist cutting radius and radial fabric reach for four circular skirt styles.

  • 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.

Private by default

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

Formula and method

For a full skirt with waist 24π cm and length 60 cm, the cut radius is 10 cm and the radial fabric reach is 72 cm.

Cut radius = waist ÷ (2π × circle fraction) − 2 cm; radial fabric reach = radius + skirt length + 2 cm.

Worked example

Enter these known values and leave the other values blank.

Type
Full circle skirt
Waist
75.39822368615503772310344119870806922073206558500253970339867021538759375086901596707283580802680963 cm
Skirt length
60 cm
Waist radius
10 cm
Fabric length
72 cm

Assumptions and limitations

  • The arithmetic retains a fixed 2 cm waist allowance and a separate 2 cm hem allowance. Fabric reach is a radial measure, not total purchased yardage. Check fabric width, fold layout, seams, shrinkage and the actual pattern before cutting.
  • Waist circumference must exceed the model’s allowance so that the cutting radius is positive. For this 64-digit numerical model, the circumference clearance above the allowance must exceed 1e-60 cm, and nonzero equation-base measurements must be at least 1e-10000 cm. Extreme nonzero values use scientific notation when fixed-decimal display is insufficient.

Common questions

How should I use this result?

The arithmetic retains a fixed 2 cm waist allowance and a separate 2 cm hem allowance. Fabric reach is a radial measure, not total purchased yardage. Check fabric width, fold layout, seams, shrinkage and the actual pattern before cutting.

Can I change units or solve an inverse?

Choose a displayed unit before entering a measurement. Clear a known quantity before entering a compatible result; only the inverse relationships retained by this model are available.

References

The fixed 2 cm waist allowance requires a strictly positive cutting radius: waist/(2*pi*type)-2 > 0. The existing positive-waist guard was insufficient for very small entered circumferences. Remove only the exact trailing promotional signup group: its two blocks contain no calculation controls, numeric results, diagrams, dynamic field references or sizing guidance. Preserve the entire functional group and all arithmetic. Exact sign predicates preserve positive lengths and cut clearances near zero. A disclosed 1e-60 cm clearance band avoids classifying within the 64-digit pi uncertainty; the existing literal scientific display fallback preserves extreme nonzero lengths without fixed-decimal display failure. Nonzero input measurements require equation-base magnitude at least 1e-10000.

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