Circle Skirt Calculator
Calculate a full, three-quarter, half or quarter circle skirt waist radius and conservative fabric layout.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
For a fraction of a circle, the waist arc is 2π × radius × that fraction. The fabric estimate uses separate quarter-circle panels and may need extra seam or pattern-matching allowance. All dimensions entered in centimetres are converted internally. Radius, cutting width and diameter are shown in inches; purchase yardage is shown in yards. The layout is a rough quarter-panel estimate; it does not include seam allowances or pattern matching.
Worked example
calculated with the default values below
Waist measurement 28 · Measurement unit Inches · Skirt length 24 · Circle fullness Full circle · Fabric width 45 · Hem allowance 2 Waist radius 4.46 in · Cutting radius including hem 30.46 in · Quarter-panel cutting width 30.5 in · Fabric to buy 3.38 yards · Waistband length 28.0 in · Cutting diameter including hem 60.9 in · Fabric layout note Quarter-panel layout estimate; allow extra for seams and pattern matching
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
r = w ÷ (2πf); R = r + L + h; Y = ⌈4f ÷ ⌊W ÷ R⌋⌉ × R ÷ 36
- r
- Waist radius (in)
- w
- Waist circumference (in)
- f
- Circle fraction
- R
- Outer radius (in)
- L
- Skirt length (in)
- h
- Hem allowance (in)
- W
- Fabric width (in)
- Y
- Fabric length (yd)
All lengths are converted to inches. Fabric is estimated as separate quarter-circle panels. If a panel does not fit the fabric width, no yardage is given.
Frequently asked questions
How should I read the units and fabric estimate?
The unit selector controls the waist, length, fabric width and hem allowance inputs. Dimensional results are always in inches and yardage is in yards. Yardage assumes quarter-circle panels placed across the fabric width; add fabric for seams, directional prints, pattern matching and the actual cutting layout.