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Circle-skirt pattern calculator

Choose the circle style, enter the waist you want to work from, and keep every measurement in one unit. The page gives the stitch and cut radii for the waist and hem, plus a simple paper-test reminder.

See the circle-skirt radii and arc angle without working through the geometry by hand.

Calculator

Circle skirt calculator inputs

Enter the waist you want to fit, the ease, skirt length, seam allowance, hem allowance, style, and unit.

Enter the measurements

Choose inches or centimetres and keep every measurement in the same unit.

Circle skirt calculator inputs
in

Enter the waist measurement you want the skirt to fit.

in

Enter the wearing ease you want to add.

in

Enter the skirt length from waist to hem.

in

Enter the seam allowance you want at the waist.

in

Enter the hem allowance you want at the outer edge.

Choose full circle, half circle, or quarter circle.

Choose inches or centimetres and keep every measurement in the same unit.

Pattern radii

Circle-skirt radii

These outputs are radii and arc angle only.

Waist stitch radius
Waist cut radius
Outer stitch radius
Outer cut radius
Arc angle
Style
Diagram from your resultThis screen schematic follows the calculated radii and selected circle style. It is not a print-scale pattern or fabric layout.
Result-linked screen schematicThis screen schematic follows the calculated radii and selected circle style. It is not a print-scale pattern or fabric layout.
Waist stitch radius
Waist cut radius
Outer stitch radius
Outer cut radius
Arc angle
Style
How to measure

Measurements

How to measure

Enter the waist measurement you want to use, the ease you prefer, the skirt length, and the seam and hem allowances. Keep the same unit throughout so the radii stay easy to read.

  • Waist is the body measurement you want to use for the skirt.
  • Ease is the extra room you want before the circle radius is calculated.
  • Skirt length runs from the waist seam to the hem.
  • Waist seam allowance and hem allowance stay separate from the measured body size.
  • Choose inches or centimetres and keep every value in the same unit.
Formula

Formula

Formula

The waist seam is a circle arc. Once the effective waist is known, the selected style sets the arc angle and the radius follows from that angle.

Start with waist + ease. Divide by the style angle to get the waist stitch radius. Then subtract waist seam allowance for the waist cut radius, add skirt length for the outer stitch radius, and add hem allowance for the outer cut radius.

  1. effective waist = waist + ease

  2. waist stitch radius = effective waist ÷ arc angle

  3. waist cut radius = waist stitch radius - waist seam allowance

  4. outer stitch radius = waist stitch radius + skirt length

  5. outer cut radius = outer stitch radius + hem allowance

full circle = 2π

half circle = π

quarter circle = π/2

Worked examples

Worked examples

Worked examples

These three sample calculations match the supported circle styles and show how the radii change with allowances.

01

Full circle

Input
28 in, 0 in, 20 in, 0.5 in, 1 in, full circle, in
Waist radius
4.456338 in
Waist cut radius
3.956338 in
Outer stitch radius
24.456338 in
Outer cut radius
25.456338 in
Arc angle
6.283185

02

Half circle

Input
70 cm, 2 cm, 60 cm, 1 cm, 2 cm, half circle, cm
Waist radius
22.918312 cm
Waist cut radius
21.918312 cm
Outer stitch radius
82.918312 cm
Outer cut radius
84.918312 cm
Arc angle
3.141593

03

Quarter circle

Input
32 in, 1 in, 24 in, 0 in, 0 in, quarter circle, in
Waist radius
21.008452 in
Waist cut radius
21.008452 in
Outer stitch radius
45.008452 in
Outer cut radius
45.008452 in
Arc angle
1.570796
Assumptions and limits

Assumptions

Assumptions and limits

The calculation stays inside a narrow circle-sewing contract, so the page can stay clear about what it does and does not cover.

  • The waist seam is circular and the skirt length is uniform.
  • The model does not choose a waistband, zipper, pockets, or other construction details.
  • The page does not decide fabric layout, fabric-width use, or how the cloth is folded.
  • The page does not give a printable pattern or make a fabric-layout claim.
  • The page shows radii and arc angle only.
Common mistakes

Mistakes

Common mistakes

  • Mixing inches and centimetres in the same calculation.
  • Putting seam allowance into the body measurement instead of leaving it separate.
  • Forgetting that ease changes the waist radius.
  • Choosing the wrong circle style for the skirt shape you want.
  • Skipping a paper test before cutting special fabric.
Paper test guidance

Paper test

Paper test guidance

Before you cut good fabric, make a quick paper check or scrap check so you can see the circles at real size.

  • Draw the waist circle and hem arc on paper.

  • Mark the seam and hem allowances in the same unit you used for the calculation.

  • Compare the radii marks with a tape measure or ruler.

  • Use scrap fabric if you want to see how your cloth behaves around the curve.