Circle Skirt Fabric & Pattern Calculator
Waist radius, cutting radius and fabric needed for a full, three-quarter, half or quarter circle skirt from waist measurement and skirt length — fold layout, hem length, whether it fits one fabric width and how many pieces to cut.
How it works
Waist radius r = (waist + ease) ÷ (2π × circle fraction) − seam allowance; outer radius R = r + SA + length + hem; full circle fits on a double fold when 2R ≤ fabric width, needing 2R of fabric
A circle skirt is a flat ring: the inner edge is the waist and the outer edge the hem, so the whole pattern follows from one formula — the waist circumference equals 2π times the inner radius, scaled by how much of a circle the skirt is. A full circle gives the most swing and the shortest waist radius; half and quarter circles are flatter and more economical; a three-quarter circle is the popular compromise. The outer radius adds length and hem. Whether it fits on one width of fabric depends on 2R: a full circle for an adult in 150 cm fabric works up to about 60 cm of length on a double fold, beyond which it is cut in halves or quarters with seams. Because much of a circle skirt hangs on the bias, it stretches unevenly — hang it before levelling and hemming.
Worked example
A full circle for a 72 cm waist with 1 cm ease, 60 cm long: waist radius 11.6 cm − 1.5 cm SA = 10.1 cm, outer radius 73.6 cm. 2R = 147 cm just fits 150 cm fabric on a double fold, so one piece and 147 cm of fabric (buy 150 cm); the hem is 4.5 m long.
Frequently asked questions
Why subtract the seam allowance from the waist radius?
The waist measurement must sit on the stitching line, which is a seam allowance outside the cut edge; cutting the inner circle smaller makes the seam line the right length. Going too small is easy to fix (trim); too big is not.
Elastic waist?
Use the hip measurement plus 2–5 cm as the “waist” so it pulls on, then gather it to the elastic; ease 0.
Related calculators
Fabric estimate — add extra for pattern matching, directional prints, shrinkage and mistakes, and check against the pattern envelope or a layout before cutting.